Pulmonx (LUNG) 10-K 15 Mar 21 2020 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Dec. 31, 2020	Mar. 04, 2021
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-39562
Entity Registrant Name	PULMONX CORPORATION
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	77-0424412
Entity Address, Address Line One	700 Chesapeake Drive
Entity Address, City or Town	Redwood City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94063
Country Region	1
City Area Code	650
Local Phone Number	364-0400
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	LUNG
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		35,689,881
Documents Incorporated by Reference	Portions of the registrant’s definitive proxy statement relating to its 2021 annual meeting of stockholders (the “2021 Proxy Statement”) are incorporated by reference into Part III of this Annual Report on Form 10-K where indicated. The 2021 Proxy Statement will be filed with the U.S. Securities and Exchange Commission within 120 days after the end of the fiscal year to which this Annual Report on Form 10-K relates.
Entity Central Index Key	0001127537
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Public Float	$ 0

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 231,561	$ 14,767
Restricted cash	231	0
Short-term marketable securities	0	13,580
Accounts receivable, net	4,228	5,511
Inventory	10,741	5,612
Prepaid expenses and other current assets	3,228	1,601
Total current assets	249,989	41,071
Property and equipment, net	1,474	902
Goodwill	2,333	2,333
Intangible assets, net	400	524
Deferred offering costs	0	1,563
Right of use assets	8,976	6,561
Other long-term assets	536	579
Total assets	263,708	53,533
Current liabilities
Accounts payable	1,472	2,681
Accrued liabilities	8,651	9,463
Income taxes payable	94	233
Deferred revenue	71	173
Current lease liabilities	2,238	446
Derivative liability	0	1,165
Total current liabilities	12,526	14,161
Deferred tax liability	62	43
Long-term lease liabilities	7,618	6,403
Credit agreement	564	0
Term loan	16,804	14,965
Total liabilities	37,574	35,572
Commitments and contingencies (Note 7)
Convertible preferred stock, $0.001 par value, no shares authorized as of December 31, 2020 and 177,985,811 shares authorized as of December 31, 2019; no shares issued and outstanding as of December 31, 2020 and 17,583,150 shares issued and outstanding as of December 31, 2019; liquidation value of $0 and $210,610 as of December 31, 2020 and December 31, 2019, respectively (Note 10)	0	205,339
Stockholders’ equity (deficit)
Preferred stock, $0.001 par value, 10,000,000 shares authorized as of December 31, 2020 and no shares authorized as of December 31, 2019; no shares issued and outstanding as of December 31, 2020 and December 31, 2019	0	0
Common stock, $0.001 par value, 200,000,000 shares and 240,000,000 shares authorized as of December 31, 2020 and December 31, 2019; 35,693,753 and 2,100,203 shares issued and outstanding as of December 31, 2020 and December 31, 2019, respectively	36	2
Additional paid-in capital	467,147	21,750
Accumulated other comprehensive income	1,685	1,373
Accumulated deficit	(242,734)	(210,503)
Total stockholders’ equity (deficit)	226,134	(187,378)
Total liabilities, convertible preferred stock and stockholders’ equity	$ 263,708	$ 53,533

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Convertible preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized (in shares)	0	177,985,811
Convertible preferred stock, shares issued (in shares)	0	17,583,150
Convertible preferred stock, shares outstanding (in shares)	0	17,583,150
Liquidation value	$ 0	$ 210,610
Stockholders’ equity (deficit)
Preferred stock, par value (in dollars per share)	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	0
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	240,000,000
Common stock, shares issued (in shares)	35,693,753	2,100,203
Common stock, shares outstanding (in shares)	35,693,753	2,100,203

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenue	$ 32,733	$ 32,595	$ 20,004
Cost of goods sold	11,531	10,181	7,718
Gross profit	21,202	22,414	12,286
Operating expenses
Research and development	7,460	6,049	6,991
Selling, general and administrative	46,074	34,203	20,347
Total operating expenses	53,534	40,252	27,338
Loss from operations	(32,332)	(17,838)	(15,052)
Interest income	213	432	21
Interest expense	(3,181)	(2,317)	(2,520)
Other income (expense), net	3,282	(617)	(916)
Net loss before tax	(32,018)	(20,340)	(18,467)
Income tax expense	213	363	12
Net loss	(32,231)	(20,703)	(18,479)
Other comprehensive income (loss)
Currency translation adjustment	318	34	126
Change in unrealized (losses) gains on marketable securities	(6)	6	0
Total other comprehensive income	312	40	126
Comprehensive loss	$ (31,919)	$ (20,663)	$ (18,353)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (3.16)	$ (11.66)	$ (11.03)
Weighted-average shares used in computing net loss per share attributable to common stockholder, basic and diluted (in shares)	10,184,841	1,776,110	1,674,779

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Convertible Debt	Common Stock	Common StockConvertible Debt	Additional Paid-In Capital	Additional Paid-In CapitalConvertible Debt	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2017	12,641,035
Beginning balance at Dec. 31, 2017	$ 140,452
Convertible Preferred Stock
Issuance of convertible preferred stock (in shares)	7,884
Issuance of convertible preferred stock	$ 83
Ending balance (in shares) at Dec. 31, 2018	12,648,919
Ending balance at Dec. 31, 2018	$ 140,535
Beginning balance (in shares) at Dec. 31, 2017			1,701,293
Beginning balance at Dec. 31, 2017	$ (149,394)		$ 2		$ 20,718		$ 1,207	$ (171,321)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	18,153		18,153
Issuance of common stock upon exercise of stock options	$ 31				31
Change in shares subject to repurchase	24				24
Stock-based compensation expense	366				366
Currency translation adjustment	126						126
Change in unrealized (losses) gains on marketable securities	0
Net loss	(18,479)							(18,479)
Ending balance (in shares) at Dec. 31, 2018			1,719,446
Ending balance at Dec. 31, 2018	$ (167,326)		$ 2		21,139		1,333	(189,800)
Convertible Preferred Stock
Issuance of convertible preferred stock (in shares)	4,934,231
Issuance of convertible preferred stock	$ 64,804
Ending balance (in shares) at Dec. 31, 2019	17,583,150
Ending balance at Dec. 31, 2019	$ 205,339
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	390,318		390,318
Issuance of common stock upon exercise of stock options	$ 528				528
Change in shares subject to repurchase	$ (281)				(281)
Repurchase of early exercised common stock options (in shares)			(9,147)
Common stock retired during the year and repurchase of early exercised common stock options (in shares)	(414)		(414)
Stock-based compensation expense	$ 364				364
Currency translation adjustment	34						34
Change in unrealized (losses) gains on marketable securities	6						6
Net loss	$ (20,703)							(20,703)
Ending balance (in shares) at Dec. 31, 2019	2,100,203		2,100,203
Ending balance at Dec. 31, 2019	$ (187,378)		$ 2		21,750		1,373	(210,503)
Convertible Preferred Stock
Issuance of convertible preferred stock (in shares)	213,876
Issuance of convertible preferred stock	$ 2,260
Conversion of convertible preferred stock into common stock (in shares)	(17,797,026)
Conversion of convertible preferred stock into common stock	$ (207,599)
Ending balance (in shares) at Dec. 31, 2020	0
Ending balance at Dec. 31, 2020	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	1,745,040		1,745,040
Issuance of common stock upon exercise of stock options	$ 2,705		$ 2		2,703
Conversion of securities into common stock (in shares)			17,797,026	2,561,484
Conversion of securities into common stock	207,599	$ 30,592	$ 18	$ 3	207,581	$ 30,589
Issuance of common stock upon initial public offering, net of issuance cost of $17,120 (in shares)			11,500,000
Issuance of common stock upon initial public offering, net of issuance costs and underwriting discount of $17,108	201,392		$ 11		201,381
Change in shares subject to repurchase	(346)				(346)
Repurchase of early exercised common stock options (in shares)			(10,000)
Stock-based compensation expense	3,489				3,489
Currency translation adjustment	318						318
Change in unrealized (losses) gains on marketable securities	(6)						(6)
Net loss	$ (32,231)							(32,231)
Ending balance (in shares) at Dec. 31, 2020	35,693,753		35,693,753
Ending balance at Dec. 31, 2020	$ 226,134		$ 36		$ 467,147		$ 1,685	$ (242,734)

Consolidated Statements of Co_2

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Payments for issuance costs		$ 329
Payments of issuance costs and underwriting discount	$ 2,462	$ 568
IPO
Payments of issuance costs and underwriting discount	$ 17,108

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net loss	$ (32,231)	$ (20,703)	$ (18,479)
Adjustments to reconcile net loss to net cash used in operating activities
Stock-based compensation expense	3,197	364	366
Change in fair value of convertible preferred stock warrant liability	0	(12)	12
Change in fair value of derivative liability	(3,190)	523	642
Allowance for doubtful accounts	(7)	(4)	(15)
Inventory write-downs	472	332	297
Depreciation and amortization expense	483	365	270
Amortization of debt discount and debt issuance costs	968	28	36
Write-off of deferred offering costs	3,030	0	0
Amortization of premiums and discounts on short-term marketable securities	(35)	(61)	0
Gain on extinguishment of convertible note	0	(32)	0
Non-cash lease expense	1,467	836	0
Net changes in operating assets and liabilities:
Accounts receivable	1,457	(2,524)	(262)
Inventory	(5,047)	(2,613)	(1,245)
Prepaid expenses and other current assets	(1,756)	(684)	21
Other assets	65	3	18
Accounts payable	592	524	(648)
Accrued liabilities	1,019	3,375	928
Income taxes payable	(155)	182	(34)
Deferred rent	0	0	(62)
Lease liabilities	(876)	(692)	0
Deferred tax liability	22	(5)	(200)
Deferred revenue	(108)	33	(39)
Net cash used in operating activities	(30,633)	(20,765)	(18,394)
Cash flows from investing activities
Purchases of investments	0	(21,450)	0
Maturities of investments	13,605	7,937	500
Purchases of property and equipment	(911)	(720)	(316)
Proceeds from sale of property and equipment	0	0	16
Net cash provided by (used in) investing activities	12,694	(14,233)	200
Cash flows from financing activities
Proceeds from borrowing under term loans, net of payment of lender fees and costs	17,291	0	0
Repayment of term loans	(17,248)	0	0
Payment of Success Fee	(1,875)	0	0
Proceeds from the issuance of convertible note, net of payment of lender fees and costs (includes $0, $6,000 and $12,000 from related party for the years ended December 31, 2020, 2019 and 2018, respectively)	32,950	6,000	12,000
Proceeds from Paycheck Protection Program loan	2,666	0	0
Repayment of Paycheck Protection Program loan	(2,666)	0	0
Debt issuance cost	(162)	0	0
Payments of deferred offering costs	(2,462)	(568)	0
Proceeds from issuance of Series G-1 convertible preferred stock, net of issuance costs of $329	0	39,671	0
Proceeds from exercise of warrants for Series C-1 convertible preferred stock	2,261	0	83
Proceeds from exercise of common stock options	2,705	528	31
Proceeds from initial public offering, net of offering costs	201,392	0	0
Payments for the repurchase of early exercised common stock options	(21)	(12)	0
Net cash provided by financing activities	234,831	45,619	12,114
Effect of exchange rate changes on cash and cash equivalents	133	22	154
Net (decrease) increase in cash and cash equivalents	217,025	10,643	(5,926)
Cash and cash equivalents at beginning of year	14,767	4,124	10,050
Cash, cash equivalents and restricted cash at end of year	231,792	14,767	4,124
Reconciliation of cash, cash equivalents and restricted cash to consolidated balance sheets:
Cash, cash equivalents and restricted cash in consolidated balance sheets	231,792	4,124	4,124
Supplemental non-cash items:
Lapse (increase) in repurchase rights of common stock	(346)	(281)	24
Purchases of property and equipment in accounts payable and accrued liabilities	65	47	0
Accrued interest for convertible note	0	496	738
Issuance of derivative instrument related to convertible notes	3,900	0	0
Conversion of convertible note into Series G-1 convertible preferred stock	0	25,133	0
Deferred offering costs in accrued liabilities and accounts payable	0	995	0
Deposit for operating lease in accounts payable	0	231	0
Operating lease right of use asset recorded on the adoption of ASC 842	0	1,181
Operating lease right of use assets obtained in exchange for new lease liabilities	3,935	6,216
Supplemental disclosure of cash flow information:
Cash paid for income taxes	259	196	226
Cash paid for interest	$ 3,059	$ 1,396	$ 1,361

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Cash Flows [Abstract]
Proceeds from related party	$ 0	$ 6,000	$ 12,000
Payments for issuance costs		$ 329

Formation and Business of the C

Formation and Business of the Company	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Formation and Business of the Company	Formation and Business of the Company The Company Pulmonx Corporation (the “Company”) was incorporated in the state of California in December 1995 as Pulmonx and reincorporated in the state of Delaware in December 2013. The Company is a commercial-stage medical technology company that provides a minimally invasive treatment for patients with severe emphysema, a form of chronic obstructive pulmonary disease (COPD). The Company’s solution, which is comprised of the Zephyr Endobronchial Valve (Zephyr Valve), the Chartis Pulmonary Assessment System (Chartis System) and the StratX Lung Analysis Platform (StratX Platform), is designed to treat a broad pool of patients for whom medical management has reached its limits and either do not want or are ineligible for surgical approaches. The Company has subsidiaries in the Cayman Islands, Germany, Switzerland, Australia, the United Kingdom, the Netherlands, Italy, France and Hong Kong. Initial Public Offering On September 30, 2020, the Company’s registration statement on Form S-1 (File No. 333-248635) relating to its initial public offering (“IPO”) of common stock became effective. The IPO closed on October 5, 2020 at which time the Company issued 11,500,000 shares of its common stock at a price of $19.00 per share, which included the issuance of shares in connection with the exercise by the underwriters of their option to purchase up to 1,500,000 additional shares. The Company received an aggregate of $218.5 million gross proceeds, before underwriting discounts, commissions and offering costs, and approximately $201.4 million in net proceeds after deducting underwriting discounts and commissions and offering costs. In addition, upon closing the IPO, all outstanding shares of the Company’s convertible preferred stock converted into 17,797,026 shares of common stock. Additionally, the $33.0 million aggregate outstanding principal amount and $0.8 million accrued interest of the 2020 Notes converted into 2,561,484 shares of common stock at a conversion price of $13.20 per share. In connection with the completion of its IPO, on October 5, 2020, the Company’s certificate of incorporation was amended and restated to provide for 200,000,000 authorized shares of common stock with a par value of $0.001 per share and 10,000,000 authorized shares of preferred stock with a par value of $0.001 per share. Liquidity and Going Concern The Company has incurred operating losses and negative cash flows from operations to date and has an accumulated deficit of $242.7 million as of December 31, 2020. During the years ended December 31, 2020, 2019 and 2018, the Company used $30.6 million, $20.8 million and $18.4 million of cash in its operating activities, respectively. As of December 31, 2020, the Company had cash and cash equivalents of $231.6 million. Historically, the Company’s activities have been financed through private placements of equity securities, debt and sale of common stock in the IPO. The Company’s consolidated financial statements have been prepared on the basis of the Company continuing as a going concern for the next 12 months. Management believes that the Company’s existing cash and cash equivalents will allow the Company to continue its planned operations for at least the next 12 months from the date of the issuance of these consolidated financial statements. Impact of the COVID-19 Pandemic The Company has been actively monitoring the novel coronavirus, or COVID-19, situation and its impact. In response to the pandemic, numerous state and local jurisdictions imposed “shelter-in-place” orders, quarantines and other restrictions. In the markets in which we operate, elective, specialty and other procedures and appointments have been suspended or canceled. In March 2020, the governor of California, where the Company’s headquarters are located, issued “stay at home” orders limiting non-essential activities, travel and business operations. Such orders or restrictions have resulted in reduced operations at the Company’s headquarters (including manufacturing facility), work stoppages, slowdowns and delays, travel restrictions and cancellation of events and have restricted the efforts of the Company’s sales representatives, thereby significantly and adversely impacting the Company’s operations. These orders and restrictions have significantly delayed and decreased the number of procedures performed using the Company’s products and otherwise adversely impacted sales and operations. The Company’s consolidated financial statements reflect judgments and estimates that could change in the future as a result of the COVID-19 pandemic. The COVID-19 pandemic has adversely impacted the Company’s business, financial condition and results of operations by decreasing and delaying substantially all procedures performed using the its products, and the Company expects the pandemic to continue to adversely impact its business, financial condition and results of operations for the foreseeable future.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared using accounting principles generally accepted in the United States of America (“GAAP”). Reverse Stock Split On September 22, 2020, the Company effected a 1-for-10 reverse stock split of the Company’s common stock and convertible preferred stock. The par value and authorized shares of common stock were not adjusted as a result of the reverse stock split. All issued and outstanding common stock, convertible preferred stock, stock options and per share amounts contained in the accompanying financial statements and notes to the financial statements have been retroactively adjusted to give effect to the reverse stock split for all periods presented. Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Significant estimates and assumptions include reserves and write-downs related to inventories, the recoverability of long term assets, valuation of equity instruments and equity-linked instruments, valuation of common stock, stock-based compensation, valuation of the convertible preferred stock warrant liability and derivative liabilities, intangible assets, goodwill, debt and related features, deferred tax assets and related valuation allowances and impact of contingencies. Fair Value of Financial Instruments The carrying amounts of the Company’s financial instruments consisting of cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate fair value due to their relatively short maturities. The convertible preferred stock warrant liability and derivative liabilities were carried at fair value based on unobservable market inputs. Based on the borrowing rates currently available to the Company for debt with similar terms and consideration of default and credit risk, the carrying value of the term loan and convertible note approximates their fair value. The fair value of marketable debt securities is estimated using Level 2 inputs based on their quoted market values (Note 4). Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the time of purchase to be cash equivalents, which include money market funds. Restricted Cash Restricted cash is comprised of cash that is restricted as to withdrawal or use under the terms of certain contractual agreements. Restricted cash for years ended December 31, 2020 consists of collateral for letters of credit issued in connection with the real estate lease in Redwood City, California. Short-Term Marketable Securities The Company determines the appropriate classification of its investments in marketable securities at the time of purchase and reevaluates such designation at each balance sheet date. The Company has classified and accounted for its marketable securities as available-for-sale. After consideration of the Company’s risk versus reward objectives and liquidity requirements, the Company may sell these securities prior to their stated maturities. As the Company views these securities as available to support current operations, the Company classifies highly liquid securities with original maturities greater than three months at the time of purchase as short-term marketable securities on the balance sheet. These securities are carried at fair value as determined based upon quoted market prices or pricing models for similar securities. Unrealized gains and losses on available for sale debt securities, if any, are excluded from earnings and are reported as a component of accumulated other comprehensive income (loss). The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity, which is included in interest income on the statements of operations and comprehensive loss. Realized gains and losses, if any, on available-for-sale securities are included in other income (expense), net. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income. There were no short-term marketable securities as of December 31, 2020. The Company did not identify any of its short-term marketable securities as other-than-temporarily impaired as of December 31, 2019. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of risk consist principally of cash, cash equivalents and accounts receivable. The Company maintains its cash and cash equivalents balances with established financial institutions and, at times, such balances with any one financial institution may be in excess of the Federal Deposit Insurance Corporation (“FDIC”) insured limits. As of December 31, 2020 and 2019, the Company also had cash on deposit with foreign banks of approximately $5.6 million and $5.2 million, respectively, that was not federally insured. The Company earns revenue from the sale of its products to distributors and other customers such as hospitals. Sales of Zephyr Valves and delivery catheters accounted for most of our revenue for the years ended December 31, 2020, 2019 and 2018. The Company’s accounts receivable are derived from revenue earned from distributors and customers. The Company performs ongoing credit evaluations of its customers’ and distributors’ financial condition and generally requires no collateral from its customers and distributors. At December 31, 2020 and 2019, no customer or distributor accounted for more than 10% of accounts receivable. For the years ended December 31, 2020, 2019 and 2018, no customer or distributor accounted for more than 10% of revenue. The Company relies on single source suppliers for the components, sub-assemblies and materials for its products. These components, sub-assemblies and materials are critical and there are no or relatively few alternative sources of supply. The Company’s suppliers have generally met the Company’s demand for their products and services on a timely basis in the past. Deferred Offering Costs Deferred offering costs, consisting of legal, accounting and other fees and costs relating to the Company’s IPO, are capitalized and recorded on the balance sheet. As of December 31, 2019, $1.6 million of deferred offering costs were recorded on the consolidated balance sheet. During the year ended December 31, 2020, the Company wrote off deferred offering costs of $3.0 million as, in May 2020, the Company withdrew its registration statement that was filed with the SEC in February 2020. After the registration statement was withdrawn in May 2020, an additional $1.8 million in deferred offering costs were incurred related to the Company’s October IPO. In connection with the IPO, all deferred offering costs incurred after May 2020 were recorded as reduction of the gross proceeds from the IPO in the additional paid-in capital on the accompanying balance sheet as of December 31, 2020. Accounts Receivable and Allowances Accounts receivable are recorded at the amounts billed less estimated allowances for doubtful accounts. The Company continually monitors customer payments and maintains an allowance for estimated losses resulting from a customer’s inability to make required payments. Company considers factors such as historical experience, credit quality, age of the accounts receivable balances, geographic related risks and economic conditions that may affect a customer’s ability to pay. As of December 31, 2020 and December 31, 2019, accounts receivable is presented net of an allowance for doubtful accounts of $0 and less than $0.1 million, respectively. Inventories Inventories are valued at the lower of cost to purchase or manufacture the inventory or net realizable value. Cost is determined using the first-in, first-out method (“FIFO”) for all inventories. Net realizable value is determined as the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The Company records write-downs of inventories which are obsolete or in excess of anticipated demand or market value based on consideration of product lifecycle stage, technology trends, product development plans and assumptions about future demand and market conditions. Inventory write-downs reduce the carrying value of inventory to its net realizable value. Property and Equipment, Net Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the assets, generally between three Impairment of Long-lived Assets The Company evaluates its long-lived assets for indicators of possible impairment by comparison of the carrying amounts to future net undiscounted cash flows expected to be generated by such assets when events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. Should an impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over the asset’s fair value or discounted estimates of future cash flows. The Company has not identified any such impairment losses to date. Goodwill Goodwill represents the excess of the purchase price over the fair value of net tangible and identified intangible assets acquired in a business combination. Goodwill is not amortized but is evaluated at least annually for impairment or when a change in facts and circumstances indicate that the fair value of the goodwill may be below its carrying value. The Company tests goodwill for impairment at the reporting unit level (“Reporting Unit”). The Company has determined that it has only one operating segment and one Reporting Unit. The operating results are reviewed only on a consolidated basis to make decisions about resources to be allocated and assess performance. Prior to performing the impairment test, the Company assesses qualitative factors to determine whether the existence of events or circumstances would indicate that it is more likely than not that the fair value of the Reporting Unit was less than the carrying amount. If after assessing the totality of events or circumstances, the Company were to determine that it is more likely than not that the fair value of the Reporting Unit is less than the carrying amount, then the Company would perform a quantitative impairment test. The quantitative impairment test involves comparing the fair value of the Reporting Unit to the carrying value. If the fair value of the Reporting Unit exceeds the carrying value of the net assets, goodwill is not impaired, and no further testing is required. If the fair value of the Reporting Unit is less than the carrying value, the Company measures the amount of impairment loss, if any, as the excess of the carrying value over the fair value of the Reporting Unit. Estimations and assumptions regarding the future performance and results of the Company’s operations, including estimates related to future sales growth, gross margin and operating expenses, and the fair value of the Company’s common stock are used in the impairment assessment. Circumstances that could reasonably be expected to negatively affect the key assumptions related to the impairment assessment include but are not limited to, (1) a significant adverse change in legal factors affecting our existing and future products or in business climate, (2) unanticipated competition, (3) an adverse action or assessment by a regulator, or (4) an adverse change in market conditions that are indicative of a decline in the fair value of the assets. Intangible Assets Intangible assets consist of developed technology and trademarks. Intangible assets were recorded at their fair values at the date of acquisition and are amortized using the straight-line method over a 15-year useful life (Note 5). Leases The Company leases its facilities and vehicles and meets the requirements to account for these leases as operating leases. The Company recognizes rent expense on a straight-line basis over the non-cancelable lease term. Where leases contain escalation clauses, rent abatements or concessions, such as rent holidays and landlord or tenant incentives or allowances, the Company applies them in the determination of straight-line rent expense over the lease term. Upon adoption of ASC 842, Leases, on January 1, 2019, the Company determined if an arrangement is a lease, or contains a lease, at inception. The asset component of the Company’s operating leases is recorded as right-of-use assets, and the liability component is recorded as current lease liabilities and long-term lease liabilities in the Company’s consolidated balance sheets. As of December 31, 2020 and 2019, the Company did not record any finance leases. ROU assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate, which is the estimated rate the Company would be required to pay for a fully collateralized borrowing equal to the total lease payments over the term of the lease, to determine the present value of future minimum lease payments. The ROU asset also includes any lease payments made to the lessor at or before the commencement date, minus lease incentives received, and initial direct costs incurred. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. For lease agreements entered into or reassessed after the adoption of ASC 842, the Company combines lease and non-lease components. Variable lease payments are expenses as incurred. Assumptions made by the Company at the commencement date are re-evaluated upon occurrence of certain events, including a lease modification. A lease modification results in a separate contract when the modification grants the lessee an additional right of use not included in the original lease and when lease payments increase commensurate with the standalone price for the additional right of use. When a lease modification results in a separate contract, it is accounted for in the same manner as a new lease. Convertible Preferred Stock The Company recorded all shares of convertible preferred stock at their respective fair values on the dates of issuance, net of issuance costs. The convertible preferred stock was recorded outside of permanent equity because while it is not mandatorily redeemable, in certain events considered not solely within the Company’s control, such as a merger, acquisition or sale of all or substantially all of the Company’s assets (each, a “deemed liquidation event”), the convertible preferred stock would become redeemable at the option of the holders of at least a majority of the then outstanding such shares. The Company had not adjusted the carrying values of the convertible preferred stock to its liquidation preference because a deemed liquidation event obligating the Company to pay the liquidation preferences to holders of shares of convertible preferred stock was not probable. Subsequent adjustments to the carrying values to the liquidation preferences would be made only when it became probable that such a deemed liquidation event would occur. All outstanding shares of the convertible preferred stock converted into common stock upon effectiveness of the IPO. Convertible Preferred Stock Warrants The Company’s convertible preferred stock warrants required liability classification and accounting as the underlying convertible preferred stock was considered contingently redeemable and might obligate the Company to transfer assets to the holders at a future date upon occurrence of a deemed liquidation event. The convertible preferred stock warrants were recorded at fair value upon issuance and were subject to remeasurement to fair value at each balance sheet date, with any changes in fair value recognized in the consolidated statements of operations and comprehensive loss. The Company continued to adjust the convertible preferred stock warrant liability for changes in fair value until the earlier of the exercise or expiration of the convertible preferred stock warrants, occurrence of a deemed liquidation event or conversion of convertible preferred stock into common stock. If all outstanding shares of the series of convertible preferred stock for which the convertible preferred stock warrants were exercisable for were converted to shares of common stock or any other security, then thereafter (a) the convertible preferred stock warrants should become exercisable for such number of shares of common stock or such other security as was equal to the number of shares of common stock or such other security that each share of convertible preferred stock was converted into, multiplied by the number of shares subject to the convertible preferred stock warrants immediately prior to such conversion, and (b) the exercise price of the convertible preferred stock warrants should automatically be adjusted to equal to the number obtained by dividing (1) the aggregate exercise price for which the convertible preferred stock warrants were exercisable immediately prior to such conversion by (2) the number of shares of common stock or such other security for which the convertible preferred stock warrants were exercisable immediately after such conversion. Revenue Recognition The Company’s revenue is generated from the sale of its products to distributors and hospitals in the United States and international markets. Under ASC 606, revenue is recognized when the customer obtains controls of promised goods or services, in an amount that reflects consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, the Company performs the following five steps as prescribed by ASC 606: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies performance obligations. A contract with a customer exists when (i) the Company enters into a legally enforceable contract with a customer that defines each party’s rights regarding the products or services to be transferred and identifies the payment terms related to these products or services, (ii) the contract has commercial substance and, (iii) the Company determines that collection of substantially all consideration for products or services that are transferred is probable based on the customer’s intent and ability to pay the promised consideration. The Company identifies performance obligations in contracts with customers, which may include its products and implied promises to provide free products and analysis services for patient scans. The transaction price is determined based on the amount expected to be entitled to in exchange for transferring the promised services or product to the customer. The Company is entitled to the total consideration for the products ordered by customers, net of early pay discounts, volume rebate adjustments and other transaction price adjustments. The Company’s payment terms to customers generally range from 30 to 60 days. Payment terms fall within the one-year guidance for the practical expedient which allows the Company to forgo adjustment of the promised amount of consideration for the effects of a significant financing component. The Company excludes taxes assessed by governmental authorities on revenue-producing transactions from the measurement of the transaction price. Assuming all other revenue recognition criteria are met, revenue is recognized when control of the Company’s products transfers to the customer. For sales where the Company’s sales representative hand delivers product directly to the hospital or medical center control transfers to the customer upon this delivery. For sales where products are shipped, control is transferred either upon shipment or delivery of the products to the customer, depending on the shipping terms and conditions. For consignment sales, control is transferred when the products are used by the customer in procedures. The Company defers revenue relating to any remaining performance obligations by the Company to the customer after delivery, such as free products and free analysis services of patient scans to determine suitability of the patients for the treatment using the Company’s Zephyr Valves. As permitted under the practical expedient, the Company does not disclose the value of unsatisfied performance obligations for contracts with an original expected length of one year or less. The Company accepts product returns at its discretion or if the product is defective as manufactured. Historically, the actual product returns have been immaterial to the Company’s financial statements. The Company elected to treat shipping and handling costs as a fulfillment cost and include them in the cost of goods sold as incurred. In those cases where the Company bills shipping and handling costs to customers, it will classify the amounts billed within revenue. The Company disaggregates its revenue by major geographic region, which has been disclosed in Note 13, “Segment Information”. The Company’s contract liabilities consist of deferred revenue for remaining performance obligations by the Company to the customer after delivery, which was $0.1 million and $0.2 million as of December 31, 2020 and December 31, 2019. The deferred revenue as of December 31, 2018 was $0.1 million, which was recognized as revenue during the year ended December 31, 2019. The deferred revenue as of December 31, 2019 of $0.2 million, which was recognized as revenue during the year ended December 31, 2020. Costs associated with product sales include commissions. The Company applies the practical expedient and recognizes commissions as expense when incurred because the expense is incurred at a point in time and the amortization period is less than one year. Commissions are recorded as selling expense. Cost of Goods Sold The Company manufactures certain products at its facility and purchases other products from third party manufacturers. Cost of goods sold consists primarily of costs related to materials, components and subassemblies, third-party costs, manufacturing overhead costs, direct labor, reserves for excess, obsolete and non-sellable inventories as well as distribution-related expenses. A significant portion of the Company’s cost of goods sold currently consists of manufacturing overhead costs. These overhead costs include the cost of quality assurance, material procurement, inventory control, facilities, equipment and operations supervision and management. Cost of goods sold also includes depreciation expense for production equipment and certain direct costs such as shipping costs. Research and Development Research and development expenses consist of compensation costs, stock-based compensation, engineering and research expenses, clinical trials and related expenses, regulatory expenses, manufacturing expenses incurred to build products for testing, allocated facilities costs, consulting fees and other expenses incurred to sustain the Company’s overall research and development programs. All research and development costs are expensed as incurred. Clinical trial costs are a significant component of the Company’s research and development expenses. The Company has a history of contracting with third parties that perform various clinical trial activities on the Company’s behalf in the ongoing development of its product candidates. The financial terms of these contracts are subject to negotiations and may vary from contract to contract and may result in uneven payment flow. The Company accrues and expenses costs for its clinical trial activities performed by third parties, including clinical research organizations and other service providers, based upon estimates of the work completed over the life of the individual study in accordance with associated agreements. The Company determines these estimates through discussion with internal personnel and outside service providers as to progress or stage of completion of trials or services pursuant to contracts with clinical research organizations and other service providers and the agreed-upon fee to be paid for such services. Advertising Costs The Company expenses the costs of advertising as incurred. Advertising expenses were $1.5 million, $0.6 million and $0.1 million for the years ended December 31, 2020, 2019 and 2018, respectively. Foreign Currency Translation and Transaction Gains and Losses The functional currencies of the Company’s wholly owned subsidiaries in the Cayman Islands and the Netherlands are the U.S. dollar. The functional currencies of the Company’s wholly owned subsidiaries in Switzerland, Germany, Australia, the United Kingdom, France and Hong Kong are the Swiss franc. The functional currency of the Company’s subsidiary in Italy is the Euro. Accordingly, asset and liability accounts of Switzerland, Germany, Australia, the United Kingdom, Italy and Hong Kong operations are translated into U.S. dollars using the current exchange rate in effect at the balance sheet date and equity accounts are translated into U.S. dollars using historical rates. The revenues and expenses are translated using the average exchange rates in effect during the period, and gains and losses from foreign currency translation adjustments are included as a component of accumulated other comprehensive income in the consolidated balance sheet. Foreign currency translation adjustments are recorded in other comprehensive income (loss) in the consolidated statements of operations and comprehensive loss and was $0.3 million, less than $0.1 million and $0.1 million during the years ended December 31, 2020, 2019 and 2018, respectively. Foreign currency transaction gains and losses are included in other income (expense), net in the consolidated statements of operations and comprehensive loss and was $0.1 million, $(0.1) million and $(0.3) million during the years ended December 31, 2020, 2019 and 2018, respectively. Stock-Based Compensation The Company accounts for stock-based compensation arrangements with employees and non-employees in accordance with ASC 718, Compensation—Stock Compensation , using a fair-value based method. The Company determines the fair value of all stock options and ESPP awards on the date of grant using the Black-Scholes option pricing model. The Company’s determination of the fair value is impacted by its common stock price as well as assumptions regarding a number of complex and subjective variables. These variables include, but are not limited to, the expected term that options will remain outstanding, expected common stock price volatility over the term of the option awards, risk-free interest rates and expected dividends. Changes in the assumptions can materially affect the fair value and ultimately how much stock-based compensation expense is recognized. These inputs are subjective and generally require significant analysis and judgment to develop. The fair value of time-based awards is recognized over the period during which an option holder is required to provide services in exchange for the option award, known as the requisite service period, which is typically the vesting period using the straight-line method. The fair value of performance-based awards is recognized over the requisite service period using the graded vesting method. The Company accounts for forfeitures as they occur. The Company issued stock options in exchange for the receipt of goods or services from non-employees. Costs for such equity instruments are measured at the fair value of the equity instruments issued on the measurement date as the Company believes that the fair value of the equity instrument is more reliably measured than the fair value of the services received. Up to December 31, 2018, the value of equity instruments issued to non-employees was determined on the earlier of the date on which there first existed a firm commitment for performance by the provider of goods and services or on the date performance is complete, using the Black-Scholes option pricing model. Therefore, the measurement of stock-based compensation issued to non-employees was subject to periodic adjustment as the underlying equity instruments vested. Stock-based compensation expense related to stock options granted to non-employees was recognized as the stock options are earned. Upon adoption of ASU 2018-07 for the periods after January 1, 2019, the Company accounts for shared-based awards granted to non-employees based on the fair value on the date of grant and recognizes compensation expense for those awards over the requisite service period, which is generally the vesting period of the respective award. Fair Value of Common Stock Prior to the Company’s IPO, the fair value of the Company’s common stock was determined by the board of directors with assistance from management and external appraisers. Management’s approach to estimate the fair value of the Company’s common stock was consistent with the methods outlined in the American Institute of Certified Public Accountants’ Practice Aid, Valuation of Privately-Held-Company Equity Securities Issued as Compensation (“Practice Aid”). Management considered several factors to estimate enterprise value, including significant milestones that would generally contribute to increases in the value of the common stock. Subsequent to the Company’s IPO, the fair value of the Company’s common stock is determined based on its closing market price. Income Taxes The Company accounts for income taxes under the asset and liability method, whereby deferred tax assets and liabilities are determined based on the difference between the consolidated financial statements and tax bases of assets and liabilities using the enacted tax rates in effect for the year in which the differences are expected to affect taxable income. A valuation allowance is established when necessary to reduce deferred tax assets when management estimates, based on available objective evidence, that it is more likely than not that the benefit will not be realized for the deferred tax assets. The Company also follows the provisions of ASC 740-10, Accounting for Uncertainty in Income Taxes . ASC 740-10 prescribes a comprehensive model for the recognition, measurement, presentation and disclosure in financial statements of any uncertain tax positions that have been taken or expected to be taken on a tax return. No liability related to uncertain tax positions is recorded on the consolidated financial statements. It is the Company’s policy to include penalties and interest expense related to income taxes as part of the provision for income taxes. Net Loss per Share Attributable to Common Stockholders Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common stock and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share

Recent Accounting Pronouncement

Recent Accounting Pronouncements	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements In August 2018, FASB issued ASU 2018-13, Fair Value Measurement (Topic 820), Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement . This ASU amends the disclosure requirement in ASC 820, Fair Value Measurement , by adding, changing or removing certain disclosures. This ASU applies to all entities that are required under this guidance to provide disclosure about recurring or nonrecurring fair value measurements. The amendments require new disclosures related to: changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period; range and weighted-average of significant unobservable inputs used to develop Level 3 fair value measurements. In addition, there are certain changes in disclosure requirements in the existing guidance. For all entities, this ASU is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted. The Company adopted ASU 2018-13 as of January 1, 2020 and the adoption had no material impact on the Company’s consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, Intangibles – Goodwill and Other: Simplifying the Test for Goodwill Impairment . The amendments eliminate Step 2 from the goodwill impairment test. The annual, or interim, goodwill impairment test is performed by comparing the fair value of a reporting unit with its carrying amount. An impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. In addition, income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit should be considered when measuring the goodwill impairment loss, if applicable. The amendments also eliminate the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails that qualitative test, to perform Step 2 of the goodwill impairment test. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. This ASU is effective for public business entities for its annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted. The Company adopted ASU 2017-04 as of January 1, 2020 and the adoption had no material impact on the Company’s consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848) (“ASU 2020-04”). The amendments in ASU 2020-04 provide optional expedients and exceptions for applying generally accepted accounting principles to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. The amendments in ASU 2020-04 are effective for all entities as of March 12, 2020 through December 31, 2022. An entity may elect to apply the amendments for contract modifications by Topic or Industry Subtopic as of any date from the beginning an interim period that includes or is subsequent to March 12, 2020, or prospectively from the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic, the amendments must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The Company may elect to apply ASU 2020-04 as its contracts referenced in London Interbank Offered Rate (“LIBOR”) are impacted by reference rate reform. The Company is currently evaluating the impact of the adoption of this ASU on the Company’s consolidated financial statements. In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity's Own Equity (Subtopic 815-40)—Accounting For Convertible Instruments and Contracts in an Entity's Own Equity (“ASU 2020-06”). ASU 2020-06 simplifies accounting for convertible instruments by removing major separation models required under current GAAP. Consequently, more convertible debt instruments will be reported as a single liability instrument with no separate accounting for embedded conversion features. ASU 2020-06 removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception, which will permit more equity contracts to qualify for it. ASU 2020-06 also simplifies the diluted net income per share calculation in certain areas. This ASU is effective for the Company for fiscal years beginning after December 15, 2023, and interim periods within those fiscal years, with early adoption permitted for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of this principle on the Company’s consolidated financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , which is intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. This ASU is effective for public business entities for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of ASU 2019-12 on the Company’s consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses . This new guidance will require financial instruments to be measured at amortized cost, and trade accounts receivable to be presented at the net amount expected to be collected. The new model requires an entity to estimate credit losses based on historical information, current information and reasonable and supportable forecasts, including estimates of prepayments. In November 2019, the FASB issued ASU 2019-10, according to which, the new standard is effective for public business entities that meet the definition of an SEC filer, excluding entities eligible to be smaller reporting companies (“SRC”) as defined by the SEC, for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. For all other entities , the new standard is effective for fiscal years beginning after December 15, 2022, and interim periods within that fiscal year. Early adoption is permitted. The Company is a SRC for fiscal year 2019 and 2020. The Company is currently evaluating the impact of the new standard on the Company’s consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value MeasurementsAssets and liabilities recorded at fair value in the consolidated financial statements are categorized based upon the level of judgment associated with the inputs used to measure their fair value. Hierarchical levels which are directly related to the amount of subjectivity associated with the inputs to the valuation of these assets or liabilities are as follows: Level 1 – Inputs are unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access as of the measurement date. Level 2 – Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; Level 3 – Unobservable inputs for the asset or liability only used when there is little, if any, market activity for the asset or liability at the measurement date. This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value. Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis – Financial assets and liabilities held by the Company measured at fair value on a recurring basis include money market funds, short-term marketable securities, convertible preferred stock warrant liability and derivative liability. Assets and Liabilities Measured and Recorded at Fair Value on a Nonrecurring Basis – The Company determines the fair value of long-lived assets held and used, such as intangible assets, by reference to independent appraisals, quoted market prices (e.g. an offer to purchase) and other factors. An impairment charge is recorded when the carrying value of the asset exceeds its fair value. As noted above, there have been no impairment charges recorded to date. Based on the borrowing rates currently available to the Company for debt with similar terms and consideration of default and credit risk, the carrying value of the term loan and convertible note payable to related party approximates their fair value and is classified as a Level 2 liability. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. The following tables summarizes the types of assets and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): December 31, 2020 Level 1 Level 2 Level 3 Total Assets: Money market funds $ 10,533 $ — $ — $ 10,533 Cash equivalents 10,533 — — 10,533 Total financial assets $ 10,533 $ — $ — $ 10,533 There were no liabilities measured at fair value on a recurring and non-recurring basis as of December 31, 2020. December 31, 2019 Level 1 Level 2 Level 3 Total Assets: Money market funds $ 6,318 $ — $ — $ 6,318 Commercial paper — 1,000 — 1,000 Cash equivalents 6,318 1,000 — 7,318 Corporate bonds — 7,105 — 7,105 Commercial paper — 6,475 — 6,475 Short-term marketable securities — 13,580 — 13,580 Total financial assets $ 6,318 $ 14,580 $ — $ 20,898 Liabilities: Preferred stock warrant liability $ — $ — $ — $ — Derivative liability — — 1,165 1,165 Total financial liabilities $ — $ — $ 1,165 $ 1,165 The following table summarizes the cost, unrealized gains and losses and fair value of marketable securities (in thousands): December 31, 2019 Amortized Cost Unrealized Losses Unrealized Gains Fair Value Corporate bonds $ 7,103 $ — $ 2 $ 7,105 Commercial paper 7,471 — 4 7,475 Marketable securities $ 14,574 $ — $ 6 $ 14,580 Amounts recognized on the consolidated balance sheet Cash equivalents $ 1,000 Short-term marketable securities 13,580 Marketable securities $ 14,580 At December 31, 2019, accrued interest on marketable securities of $0.1 million was included in prepaid expenses and other current assets on the consolidated balance sheet. The Company did not have marketable securities as of December 31, 2020. The Company values the convertible preferred stock warrant liability (Note 9) using the Black-Scholes Merton option-pricing model. The expected term for these warrants is based on the remaining contractual life of these warrants. The expected volatility assumption was determined by examining the historical volatility for industry peers, as the Company does not have a trading history for its common stock. The risk-free interest rate assumption is based on U.S. Treasury investments whose term is consistent with the expected term of the warrants. The expected dividend assumption is based on the Company’s history and expectation of dividend payouts. The fair value of the Series C-1 convertible preferred stock warrants was determined using the following assumptions: December 31, 2019 Risk-free interest rate 1.6 % Remaining contractual life (in years) 0.1 Dividend yield 0 % Volatility 57.5 % Derivative liabilities include derivatives associated with the Company’s Success Fee Agreement with Oxford Finance LLC (Note 6) and the 2020 Notes derivative liability (Note 6). The Company valued Success Fee derivative liability based on the Success Fee amount of $1.9 million and the probability and estimated timing of a liquidity event. The probability of occurrence of a Liquidity Event was estimated to be up to 65% before the expiration of the agreement as of December 31, 2019. Changes in the estimated probability may result in an increase or decrease in the fair value of the derivative liability. On October 5, 2020, the Success Fee derivative liability was settled upon the Company paying $1.9 million pursuant to the Success Fee Agreement to Oxford Finance LLC. The Company valued the 2020 Notes derivative liability using the “with and without” methodology. The “with and without” methodology involves valuing the convertible note on an as is basis and then valuing the 2020 Notes without each individual embedded derivative. The difference between the value of the 2020 Notes with the embedded derivatives and the value without each individual embedded derivative equals the fair value of that embedded derivative. In April 2020, the Company valued the embedded derivatives using a Monte Carlo Simulation (“MCS”). The first step of each simulation was to forecast the Company’s Series G-1 convertible preferred stock price through the expiration of the 2020 Notes. In order to estimate the future share price of the Series G-1 convertible preferred stock, the Company applied a “random walk” model based upon a Geometric Brownian Motion process with a constant drift. The fair value of the 2020 Notes derivative liability was determined using the following assumptions: April 17, 2020 Risk-free interest rate 0.2 % Current Series G-1 convertible preferred stock value per share $ 0.84 Series G-1 convertible preferred stock volatility 34.4 % Upon the closing of the IPO in October 2020, the 2020 Notes converted pursuant to a qualified initial public offering (Note 6). As a result, the Company concluded that the 2020 Notes derivative had no value upon the closing of the IPO, because value of the notes with and without the such derivative was the same. The change in fair value of the convertible preferred stock warrant liability and derivative liabilities is summarized below (in thousands): Convertible Preferred Stock Warrant Liability Success Fee Derivative Liability 2020 Notes Derivative Liability Beginning fair value, January 1, 2018 $ — $ — $ — Change in fair value 12 642 — Ending fair value, December 31, 2018 $ 12 $ 642 $ — Beginning fair value, January 1, 2019 12 642 — Change in fair value (12) 523 — Ending fair value, December 31, 2019 $ — $ 1,165 $ — Beginning fair value, January 1, 2020 — 1,165 — Fair value at inception — — 3,900 Change in fair value — 710 (3,900) Payment of Success Fee — (1,875) — Ending fair value, December 31, 2020 $ — $ — $ —

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	Balance Sheet Components Cash and Cash Equivalents The Company’s cash and cash equivalents consist of the following (in thousands): December 31, 2020 2019 Cash $ 221,028 $ 7,449 Cash equivalents: Money market funds 10,533 6,318 Commercial paper — 1,000 Total cash and cash equivalents $ 231,561 $ 14,767 Inventory Inventory consists of the following (in thousands): December 31, 2020 2019 Raw materials $ 3,342 $ 1,950 Work in process 227 180 Finished goods 7,172 3,482 Total inventory $ 10,741 $ 5,612 Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following (in thousands): December 31, 2020 2019 Prepaid expenses $ 381 $ 436 Prepaid insurance 2,131 12 VAT receivable 339 387 Other current assets 377 766 Total prepaid expenses and other current assets $ 3,228 $ 1,601 Property and Equipment, Net Property and equipment, net consist of the following (in thousands): December 31, 2020 2019 Machinery and equipment $ 1,447 $ 1,269 Computer equipment and software 1,062 848 Furniture and fixtures 229 168 Leasehold improvements 57 57 Construction in progress 452 — Total 3,247 2,342 Less: accumulated depreciation (1,773) (1,440) Property and equipment, net $ 1,474 $ 902 Depreciation expense for the years ended December 31, 2020, December 31, 2019 and December 31, 2018 was $0.3 million, $0.2 million and $0.1 million, respectively. Goodwill Goodwill was $2.3 million as of December 31, 2020 and December 31, 2019 arising from the Company’s acquisition of Emphasys Medical, Inc, in March 2009. No goodwill impairment losses have been recognized since the acquisition. There were no acquisitions or dispositions of goodwill in 2020 and 2019. The Company performed an annual test for goodwill impairment in the fourth quarter of the fiscal years ended December 31, 2020 and December 31, 2019 and determined that goodwill was not impaired. Intangible Assets Intangible assets consist of the following (in thousands): December 31, 2020 Gross Carrying Value Accumulated Amortization Net Carrying Value Developed technology $ 1,658 $ (1,299) $ 359 Trademarks 191 (150) 41 Total intangible assets $ 1,849 $ (1,449) $ 400 December 31, 2019 Gross Carrying Value Accumulated Amortization Net Carrying Value Developed technology $ 1,658 $ (1,188) $ 470 Trademarks 191 (137) 54 Total intangible assets $ 1,849 $ (1,325) $ 524 Amortization expense relating to the intangibles totaled $0.1 million during each of the years ended on December 31, 2020, 2019 and 2018. Future amortization expense is as follows (in thousands): Year Ending December 31, 2021 $ 123 2022 123 2023 123 2024 31 Total amortization expense $ 400 Accrued Liabilities Accrued liabilities consist of the following (in thousands): December 31, 2020 2019 Accrued employee bonuses $ 2,374 $ 3,064 Accrued vacation 1,810 1,098 Other accrued personnel related expenses 1,368 705 Accrued professional fees 1,313 1,342 Accrued interest — 1,708 Sales taxes, franchise tax and VAT 521 762 Liability for early exercise of stock options 629 304 Other 636 480 Total accrued liabilities $ 8,651 $ 9,463

Long Term Debt and Convertible

Long Term Debt and Convertible Notes	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Long Term Debt and Convertible Notes	Long Term Debt and Convertible Notes Term Loan Oxford Finance Loan In August 2014, the Company entered into a Loan and Security Agreement with Oxford Finance LLC for up to $20.0 million in term loans. In 2014, the Company borrowed $15.0 million and had the ability to draw an additional $5.0 million conditioned upon the achievement of a revenue milestone. The period during which the Company could draw an additional $5.0 million ended on November 30, 2015 without the Company borrowing the additional $5.0 million. The term loan bore interest at 8.96% and had a five-year term. The first 36 months were interest only payments followed by 24 months of equal payments of principal and interest. A final payment of 8.50% of the term loan amount is due at maturity and is being accreted using the effective interest rate method. The term loan is collateralized by assets, including cash and cash equivalents, accounts receivable and property and equipment. In May 2017, the Company entered into a First Amendment to Loan and Security Agreement that extended the interest only period through June 2018 and included an additional fee of $0.1 million due upon maturity. The amendment was accounted for as a debt modification and no gain or loss is recognized in the Company’s financial statements. In May 2018, the Company entered into Second and Third Amendments to Loan and Security Agreement that extended the interest only period through May 2019 and the maturity date to July 1, 2020. The amendment was accounted for as a debt modification and no gain or loss is recognized in the Company’s financial statements. The Company had the option to further extend the interest only period through March 2020 and the maturity date to May 1, 2021, provided that no event of default had occurred. The loan bears interest at an annual rate equal to the greater of (i) 8.71% and (ii) the sum of (a) the greater of the one month U.S. LIBOR rate on the last business day of the month that immediately precedes the month in which the interest will accrued and 1.85% plus (b) 6.86%. In May 2019, the Company elected to extend the interest only period of the term loan through March 2020 and the maturity date to May 2021. The incremental amendment fee, due at maturity, increased to $0.8 million from $0.4 million when the Company extended the interest only period through March 2020. As of February 20, 2020 (repayment date), December 31, 2019 and December 31, 2018, the term loan had an annual effective interest rate of 11.11% per year, 11.11% per year and 11.17% per year, respectively. In connection with the original agreement in August 2014, the Company also entered into the Success Fee Agreement. In the event of a sale or other disposition by the Company of all or substantially all of its assets, a merger or consolidation, or an initial public offering (a “Liquidity Event”), before the termination of the agreement on August 28, 2021, the Company is required to pay up to $2.5 million (the “Success Fee”) to Oxford Finance LLC. The Success Fee is equal to 6.25% of the term loan if the Liquidity Event occurs within 18 months of August 28, 2014, 8.75% if the Liquidity Event occurs after 18 months and within 3 years of August 28, 2014, and 12.50% if the Liquidity Event occurs after the third anniversary of August 28, 2014. As of December 31, 2019, the maximum amount of Success Fee subject to a potential payout was $1.9 million. This agreement has been identified as a freestanding derivative under ASC 815, Derivatives (“Success Fee”) and is remeasured to its fair value at the end of each reporting period and any change in fair value is recognized as change in other income (expense), net in the statements of operations and comprehensive loss (Note 4). The fair value of the Success Fee derivative liability as of December 31, 2019 was $1.2 million. On October 5, 2020, in connection with the IPO, the Company paid $1.9 million pursuant to the Success Fee Agreement to Oxford Finance LLC. The Loan and Security Agreement contained customary affirmative and negative covenants and events of default. As of December 31, 2019, the Company was in default with a covenant in the Loan and Security Agreement resulting from its failure to maintain cash balances outside the United States within the levels set forth in the Loan and Security Agreement. This event of default was waived by Oxford Finance LLC. On February 20, 2020, the Company repaid its entire obligation under the term loan agreement with Oxford Finance LLC amounting to $17.3 million, including outstanding loan amount of $15.0 million, final payment of $1.3 million, amendment fees of $0.9 million and accrued interest of $0.1 million. The repayment of the obligation under the term loan agreement with Oxford Finance LLC was accounted as extinguishment and the Company recorded a loss on extinguishment of $0.4 million included in interest expense in the consolidated statements of operations and comprehensive loss. The term loan consisted of the following (in thousands): December 31, 2020 2019 Term loan $ — $ 15,000 Less: debt issuance costs — (27) Less: deferred financing costs — (8) Term loan $ — $ 14,965 The Company incurred fees and legal expenses of $0.1 million in connection with the Agreement and Amendments, which are recorded as deferred financing costs and amortized to interest expense. The Company also paid $0.2 million in fees to the lender which is reflected as a discount on the debt and is being accreted over the life of the term loan. In 2020, 2019 and 2018, the Company recorded interest expense related to deferred financing and debt issuance costs of less than $0.1 million. Interest expense on the term loan amounted to $0.4 million, $1.7 million and $1.7 million during the years ended December 31, 2020, December 31, 2019 and December 31, 2018, respectively. CIBC Loan On February 20, 2020, the Company executed a Loan and Security Agreement (the “CIBC Agreement”) with Canadian Imperial Bank of Commerce (“CIBC”) to raise up to $32.0 million in debt financing (“CIBC Loan”) consisting of $17.0 million advanced at the closing of the agreement (Tranche A), with the option to drawing up to an additional $8.0 million (Tranche B) on or before February 20, 2022. The term loan also provided for an additional financing tranche (Tranche C) of up to $7.0 million on or prior to February 20, 2022, which was conditioned upon achieving a trailing six-month revenue of at least $20.0 million as of the date of any Tranche C borrowing. The availability of Tranche B and Tranche C is further conditioned upon the joining of Pulmonx International Sàrl to the CIBC Agreement and the execution by Pulmonx International Sàrl of Swiss-law collateral documentation in favor of CIBC. The CIBC Loan originally had a five-year term maturing on February 20, 2025, which included 24 months of interest only payments followed by 36 months of equal payments of principal and interest. The interest only period can be extended to 36 months if the Company achieves three-month trailing revenue of at least $20.0 million as of February 20, 2022. The CIBC Loan bears interest at a floating rate equal to 1.0% above the Wall Street Journal Prime Rate at any time. The Tranche C loan will bear interest at a floating rate equal to 1.5% above the Wall Street Journal Prime Rate at any time. The CIBC Loan is collateralized by substantially all of the Company’s assets, including cash and cash equivalents, accounts receivable, intellectual property and equipment. The Company may prepay the loan, subject to certain requirements. The CIBC Agreement includes customary restrictive covenants, financial covenants, events of default and other customary terms and conditions. In April 2020, the Company entered into a First Amendment to CIBC Agreement that changed the maturity date to March 15, 2022, which shall be automatically extended to February 20, 2025 if the maturity of all outstanding convertible notes (see below) is extended to a date no earlier than May 21, 2025 or all convertible notes have been converted into convertible preferred stock of the Company. The Company paid to CIBC an amendment fee of $0.2 million. The Tranche B drawing was amended and is conditioned to achieving a trailing six-month revenue of at least $15.0 million as of the date of any Tranche B borrowing. On the date of drawing Tranche B Loan or Tranche C Loan, the Company will pay a structuring fee in an amount equal to 1.0% of the amount of Tranche B Loan or Tranche C Loan. The amendment was accounted for as a debt modification and no gain or loss was recognized. As of December 31, 2020, the CIBC Loan had an annual effective interest rate of 5.16% per year. In December 2020, to address certain post-close covenants for which the Company was not in compliance, the Company entered into a Second Amendment to the CIBC Agreement that extended the compliance date for certain post-close covenants to June 30, 2021. The financial covenants in the CIBC Agreement require the Company to have revenue for the trailing three-month period ending on March 31, 2021, and the last day of each June, September, December and March thereafter of not less than the greater of (i) the amount equal to 80% of the revenue for the trailing three-month period ending on such day, as set forth in the annual projections delivered to the CIBC, and approved by CIBC, and (ii) the revenue for the trailing three-month period ending on the last day of the month for which this covenant had most recently been tested prior to such day. Further, the Company on and at all times after April 17, 2020, maintain unrestricted cash in an aggregate amount equal to or greater than the Adjusted EBITDA loss as defined in the CIBC Agreement for the four-month period ending on any date of determination. As of December 31, 2020, the Company was in compliance with all the covenants contained in the CIBC Agreement. The CIBC Loan as of December 31, 2020, consisted of the following (in thousands): December 31, 2020 Term loan $ 17,000 Less: debt issuance costs (196) Term loan $ 16,804 The Company paid $0.3 million fees to the lender and third parties, including the amendment fee of $0.2 million, which is reflected as a discount on the CIBC Loan and is being accreted over the life of the term loan using the effective interest method. During the year ended December 31, 2020, the Company recorded interest expense related to debt discount and debt issuance costs of CIBC Loan of $0.1 million. Interest expense on the CIBC Loan amounted $0.7 million during the year ended December 31, 2020. Credit Agreement In April 2020, Pulmonx International Sàrl, a wholly-owned subsidiary of the Company, entered into a COVID-19 Credit Agreement with UBS Switzerland AG to receive up to 0.5 million Swiss Francs ($0.5 million U.S. dollar equivalent) under Swiss Federal Government program to mitigate the economic impact of the spread of the coronavirus. In May 2020, Pulmonx International Sàrl received 0.5 million Swiss Francs ($0.5 million U.S. dollar equivalent) under the COVID-19 Credit Agreement. The COVID-19 Credit Agreement will bear no interest and is payable within 60 months after receipt of funds. As of December 31, 2020, Pulmonx International Sàrl did not make any repayment of credit agreement. Paycheck Protection Program On April 16, 2020, the Company received $2.7 million in support from the Paycheck Protection Program (the “PPP”) established by the U.S. federal government as part of the CARES Act for the PPP. Because the U.S. government subsequently changed its position and guidelines related to the PPP and publicly traded companies, the Company repaid the loan on May 1, 2020. Convertible Note In May 2017, the Company entered into a Second Lien Loan and Security Agreement with Boston Scientific Corporation, an investor, for up to $30.0 million in term loans. The loans under this agreement are subordinated to the term loan with Oxford Finance LLC and are also collateralized by assets, including cash and cash equivalents, accounts receivable and property and equipment. Under the Agreement, Boston Scientific Corporation agreed to make one or more term loans to the Company during the period beginning in May 2017 and ending on May 13, 2022, the maturity date (the “Term Loans”). The principal amount outstanding under the Term Loans drawn prior to June 30, 2018 accrued no interest from the date of such Term Loan through and including June 30, 2018. Beginning on July 1, 2018, all Term Loans accrued interest at a fixed rate of 8.96%. Interest accrues until such Term Loan is converted to stock or paid in full. Each Term Loan is evidenced by a separate Secured Convertible Promissory Note and is repayable, convertible and exchangeable. If the Company completes any Qualified Equity or Debt Financing or any Change of Control, Liquidation or Prepayment Conversion occurs, outstanding principal and accrued interest on the loans are convertible at Boston Scientific Corporation’s option into shares of either (1) the Series F-1 convertible preferred stock or, if the shares of Series F-1 convertible preferred stock are not the most senior series of preferred stock of the Company then issued and outstanding (2) the most senior series of preferred stock of the Company then issued and outstanding (“Conversion Stock”). The Conversion Stock Per Share Price is defined as (A) with respect to a Qualified Equity Financing, the lowest price per share of Conversion Stock paid by any investor in such Qualified Equity Financing, (B) with respect to a Change of Control or Liquidation, the total amount distributed, paid or to be paid to the stockholders of the Company on account of the stock held by them in connection with such Change of Control or Liquidation, divided by the fully-diluted share count of the Company on the Conversion Date or (C) with respect to a Prepayment Conversion, $230,000,000 divided by the fully-diluted share count of the Company on the Conversion Date. Subject to Boston Scientific Corporation’s conversion rights, the Company had the option to prepay all of the Term Loans, at any time. In conjunction with the Second Lien Loan and Security Agreement, the Company and Boston Scientific entered into a No Shop Agreement such that from the date of execution of the agreement through the earlier of the Company’s submission of the final module of its Premarket Approval application to the FDA and March 31, 2018, the Company would not sign a term sheet or engage in discussions to sell the Company. In addition, Boston Scientific’s Right of First Negotiation, originally received as part of the Preferred Series F-1 financing, was amended to shorten the period it has to exercise its Right of First Negotiation from 10 to 5 business days, and to shorten the Exclusive Negotiation Period from 75 to 45 days with respect to the initial notice from the Company that it intends to pursue a change in control or IPO. For subsequent notices from the Company, Boston Scientific has 10 days to exercise its right of first negotiation, and 75 days to enter into definitive agreements for a change in control transaction. The Company borrowed $6.0 million in 2017, $12.0 million in 2018 and $6.0 million in January 2019 under the Second Lien Loan and Security Agreement with Boston Scientific Corporation. In April 2019, all the Term Loans and accrued interest of $25.1 million under the agreement converted into 1,903,935 shares of Series G-1 convertible preferred stock at a price of $13.2 per share at the option of Boston Scientific Corporation upon the occurrence of Series G-1 convertible preferred stock financing, which met the definition of Qualified Equity Financing in the Second Lien Loan and Security Agreement (Note 10). This conversion was accounted as debt extinguishment and the Company recognized less than $0.1 million extinguishment gain upon such conversion. The Company incurred fees and legal expenses of $0.1 million in connection with the Agreement, which are reported on the balance sheet as a direct deduction from the face amount of the convertible note. Amortization of the issuance costs are calculated using the effective interest rate method over the term of the note and recorded as a non-cash interest expense. In 2018, the Company accrued interest expense of $0.8 million, which was included in convertible notes at December 31, 2018. As of December 31, 2018, the Term Loans had an annual effective interest rate of 7.47% per year. The Second Lien Loan and Security Agreement contains customary affirmative and negative covenants and events of default. As of December 31, 2019 and December 31, 2018, the Company was in compliance with all the covenants contained in the Second Lien Loan and Security Agreement. In January 2020, the Company terminated the Second Lien Loan and Security Agreement. 2020 Notes In April 2020, the Company entered into a Note Purchase Agreement and Convertible Promissory Notes (collectively the “2020 Notes Agreement”) with certain investors (the “Lenders”) to issue convertible promissory notes (the “2020 Notes”) for a maximum aggregate amount of $66.0 million. In April 2020, the Company received $33.0 million in gross proceeds from issuance of the 2020 Notes. Upon meeting customary closing conditions, the Company can draw up to an additional $33.0 million, provided that any such draw be for no less than $5.0 million on or prior to April 17, 2022. All unpaid interest and principal will be due and payable upon request of the majority of Lenders (“Majority Holders”) on or after the earlier of April 17, 2022 or an event of default. The 2020 Notes accrue interest at a rate equal to 2.0% above the Wall Street Journal Prime Rate. The Company may prepay the 2020 Notes prior to April 17, 2022 only with the consent of the Majority Holders. In the event that the Company issued and sold shares of its convertible preferred stock to investors with total proceeds of not less than $30.0 million (excluding the conversion of the 2020 Notes or other convertible securities issued for capital raising purposes) (a “Qualified Financing”), then the outstanding principal amount of the 2020 Notes and any unpaid accrued interest should automatically convert into the same class and series of convertible preferred stock sold in the Qualified Financing at a conversion price equal to the lesser of (i) the price per share paid for preferred stock in the Qualified Financing multiplied by either 85% if the conversion took place within 18 months of the Initial Closing, or 80% otherwise, and (ii) $13.20 per share. In the event the Company sold shares of convertible preferred stock in a transaction that did not constitute a Qualified Financing (a “Non-Qualified Financing”), then the Majority Holders would have the option to treat such Non-Qualified Financing as a Qualified Financing; provided, that, the Majority Holders might not elect to convert the 2020 Notes held by any Significant Holder in the Non-Qualified Financing without such Significant Holder’s consent unless such Non-Qualified Financing (a) was led by an investor who was not currently a stockholder of the Company and (ii) raised at least $10.0 million in total proceeds from investors who were not currently stockholders of the Company. A Significant Holder was a holder of the 2020 Notes equal to or greater than $20 million. If there was an event of default, then the conversion of the 2020 Notes would be at a conversion price equal to the lesser of: a. the price per share paid for convertible preferred stock by the Investors in the Non-Qualified Financing multiplied by 75% , and b. the Series G-1 convertible preferred stock conversion price of $13.20 per share multiplied by 75%. Upon an initial public offering which resulted in net proceeds of not less than $30.0 million (a “Qualified IPO”), the outstanding 2020 Notes and any unpaid accrued interest should automatically convert in whole into shares of the Company’s common stock at a conversion price equal to the lesser of (i) price per share paid for common stock in the Qualified IPO multiplied by either 85% if the conversion took place within 18 months of the Initial Closing, or 80% otherwise, and (ii) $13.20 per share. Upon an initial public offering that did not constitute a Qualified IPO (a “Non-Qualified IPO”), the Majority Holders should have the option to treat such Non-Qualified IPO as a Qualified IPO; provided that if there was an event of default, conversion of the 2020 Notes would be at a conversion price equal to the lesser of: a. the price per share paid for common stock in the Non-Qualified IPO multiplied by 75%, and b. the Series G- 1 convertible preferred stock conversion price of $13.20 per share multiplied by 75%. At any other time upon the election of the Majority Holders or a Significant Holder, the outstanding principal amount of the 2020 Notes and any unpaid accrued interest would convert in whole into the Company’s Series G-1 convertible preferred stock at the Series G-1 convertible preferred stock conversion price of $13.20 per share. If there was an event of default prior to selection of such option, the 2020 Notes would be converted at a conversion price equal to the Series G-1 convertible preferred stock conversion price of $13.20 per share multiplied by 75%. Upon any event of default, the Majority Holders could, at written notice to the Company, declare the principal and unpaid accrued interest under the 2020 Notes immediately due and payable. The 2020 Notes included embedded derivatives that are required to be bifurcated from the 2020 Notes and accounted for separately as a single, compound embedded derivative instrument under ASC 815, Derivatives (“2020 Notes derivative liability”). The Company determined that the share settled redemption in the case of a financing or an IPO discussed above represented an embedded derivative that was not clearly and closely related to the debt host and had accounted for these settlement alternatives as separate embedded derivative liability. The fair value of the 2020 derivative liability of $3.9 million was recorded on the issuance date of the 2020 Notes resulting in a debt discount, which was reported as a direct deduction from the face amount of the 2020 Notes. The 2020 derivative liability was remeasured to its fair value at the end of each reporting period and any change in fair value was recognized in other income (expense), net in the statements of operations and comprehensive loss (Note 4). The change in fair value of $3.9 million during the year ended December 31, 2020 was recorded as a component of other income (expense), net in the condensed consolidated statements of operations and comprehensive loss. Upon the closing of the IPO in October 2020, the 2020 Notes converted pursuant to a qualified initial public offering. As a result, the Company concluded that the 2020 Notes derivative had no value upon the closing of the IPO, because value of the notes with and without the such derivative was the same. At December 31, 2020, the Company retained the ability to draw up to an additional $33.0 million under the 2020 Notes Agreement until the maturity date in April 2022. The Company’s obligations with respect to the 2020 Notes are unsecured and subordinated to its obligations with respect to the CIBC Loan. The 2020 Notes have customary events of default. The Company incurred debt issuance costs of $0.1 million in connection with the 2020 Notes Agreement, which were reported on the balance sheet as a direct deduction from the face amount of the 2020 Notes. During the year ended December 31, 2020, the Company recorded interest expense of $1.6 million on the 2020 Notes, consisting of $0.8 million of contractual interest expense and $0.8 million amortization of debt discount and debt issuance costs. Before the conversion upon the IPO, the 2020 Notes had an annual effective interest rate of 12.33% per year. In connection with the closing of the IPO, the $33.0 million aggregate outstanding principal amount and $0.8 million accrued interest of the 2020 Notes converted into 2,561,484 shares of common stock at a conversion price of $13.20 per share. Contractual Maturities of Financing Obligations As of December 31, 2020, the aggregate future payments under the CIBC Loan and Credit Agreement (including interest payments) are as follows (in thousands): 2021 723 2022 17,146 2023 — 2024 — 2025 564 Total 18,433 Less: unamortized debt discount (196) Less: interest (869) Term loan, convertible notes, and credit agreement $ 17,368

Leases, Commitments and Conting

Leases, Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases, Commitments and Contingencies	Leases, Commitments and Contingencies The Company has a lease for its headquarters location in Redwood City, California. In October 2019, the Company renewed its lease for the headquarters location in Redwood City, California for an additional five years commencing in August 2020 and expiring in July 2025. The monthly base rent during the renewed term is $0.1 million and is subject to an annual increase of 3.5%. The Company is responsible for its share of real estate taxes, common area maintenance and management fees. The Company is eligible to receive a tenant improvement allowance of $0.2 million on commencement of the renewal term in August 2020. During 2013, the Company entered into a five-year lease for office facilities in Switzerland. The Company had an option to extend the lease through January 2022, which was not exercised by the Company. Per the lease terms, in the event the option to extend is not exercised, the lease remains in force and can be terminated with a 12-month’s notice. In April 2020, the Company executed a sublease for another office facility in Redwood City, California for a three-year term commencing on June 1, 2020. The lease agreement provides for early termination if the Company or Sublandlord elects to terminate the lease by providing the other party at least 180 days prior written notice. The early termination may only occur on or after the expiration of the 18th full calendar month of the sublease term. The lease term for this lease is 18 months as the possible exercise of the early termination option by the Sublandlord is not within the Company’s control. The monthly base rent during the term is less than $0.1 million and is subject to an annual increase of 3.5%. The Company is responsible for its share of real estate taxes, common area maintenance and management fees. In September 2020, the Company amended a sublease agreement entered in April 2020, to include additional facility space in Redwood City, California for a four-year term. The amendment was accounted as a separate sublease agreement. The sublease agreement contains a rent free period through February 14, 2021, after which rent is approximately $0.1 million per month and is subject to an annual increase of 3.5%. The Company is responsible for its share of real estate taxes, common area maintenance and management fees. The Company is eligible to receive a tenant improvement allowance of $0.6 million to fund facility enhancements. The sublease agreement can be extended for an additional twelve The Company has leases on two vehicle leases with lease terms ranging from 2 to 4 years. Rent expense for the year ended December 31, 2018 under ASC 840 was $1.0 million. Operating lease cost consists of the following (in thousands): Years Ended December 31, 2020 2019 Operating lease cost $ 2,078 $ 1,037 Short-term lease cost 12 13 Variable lease cost 337 234 Total lease cost $ 2,427 $ 1,284 The following table summarizes a maturity analysis of our lease liabilities showing the aggregate lease payments as of December 31, 2020 (in thousands): 2021 $ 2,769 2022 2,069 2023 2,795 2024 2,589 2025 1,007 Total minimum lease payments 11,229 Less: Amount of lease payments representing interest 1,373 Present value of future minimum lease payments $ 9,856 Less: Current lease liabilities $ 2,238 Long-term lease liabilities $ 7,618 The following table summarizes balance sheet and other information related to our operating leases as (in thousands, except weighted average data): December 31, 2020 2019 Right of use asset $ 8,976 $ 6,561 Weighted average remaining lease term (years) 4.13 5.54 Weighted average discount rate (percent) 6.1 7.0 The following table summarizes other supplemental information related to our operating leases (in thousands): Years Ended December 31, 2020 2019 Cash paid for amounts included in the measurement of lease liabilities included in cash flows used in operating activities $ 1,494 $ 893 Right-of-use assets obtained in exchange for lease liabilities $ 3,935 $ 7,316 Contingencies From time to time, the Company may be a party to various litigation claims in the normal course of business. Legal fees and other costs associated with such actions are expensed as incurred. The Company assesses, in conjunction with legal counsel, the need to record a liability for litigation and contingencies. Accrual estimates are recorded when and if it is determinable that such a liability for litigation and contingencies are both probable and reasonably estimable. In December 2018, a former distributor outside the United States filed suit alleging the Company’s subsidiary, PulmonX International Sàrl, conducted unfair competitive practices and violated the exclusive distribution rights as a result of the subsidiary’s termination of its distribution agreement. The complaint seeks pecuniary and non-pecuniary damages. The Company is in the initial stages of evaluating this matter and does not believe the impact of any such matter will be material to the Company’s results of operation or financial position.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income before the provision for income taxes consists of the following (in thousands): Years Ended December 31, 2020 2019 2018 Domestic $ (28,029) $ (17,142) $ (12,527) Foreign (3,989) (3,198) (5,940) Total loss before provision for taxes $ (32,018) $ (20,340) $ (18,467) The components of income tax expense are as follows (in thousands): Years Ended December 31, 2020 2019 2018 Current: Federal $ — $ — $ — State 9 10 2 Foreign 185 358 207 Total current expense 194 368 209 Deferred: Federal 6 7 (222) State 6 27 4 Foreign 7 (39) 21 Total deferred expense 19 (5) (197) Total income tax expense $ 213 $ 363 $ 12 The reconciliation between the federal statutory rate and the Company’s effective tax rate is summarized below: Years Ended December 31, 2020 2019 2018 Federal statutory rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 10.2 % 2.7 % 1.0 % Foreign earnings at different rates (3.9) % (4.8) % (8.0) % Tax credits 0.6 % 0.6 % 0.9 % Permanent differences (0.3) % (0.4) % (0.3) % Prior year true-up 0.3 % 0.0 % (2.9) % Change in valuation allowance (40.5) % (20.9) % 10.7 % Expiration of net operating loss carryforwards and credits 0.0 % 0.0 % (22.5) % Entity restructuring 11.9 % 0.0 % 0.0 % Effective tax rate (0.7) % (1.8) % (0.1) % Deferred income taxes arise from temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax reporting purposes, as well as operating losses and tax credit carryforwards. Significant components of the Company’s deferred tax assets and liabilities for federal and state income taxes are as follows (in thousands): December 31, 2020 2019 2018 Deferred tax assets: Net operating loss carryforwards $ 30,400 $ 22,500 $ 19,519 Tax credit carryforwards 5,240 4,896 4,659 Other 6,675 1,926 850 Gross deferred tax assets 42,315 29,322 25,028 Less: valuation allowance (41,922) (28,953) (24,736) Deferred tax assets 393 369 292 Deferred tax liabilities: Depreciation (27) (23) (17) Goodwill (428) (389) (323) Net deferred tax liabilities $ (62) $ (43) $ (48) The Company has established a full valuation allowance against its U.S. net deferred tax assets due to the uncertainty surrounding the realization of such assets. Realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Accordingly, the U.S. net deferred tax assets have been fully offset by a valuation allowance of $41.9 million as of December 31, 2020. The valuation allowance increased by $13.0 million and $4.2 million and decreased by $2.0 million for the years ended December 31, 2020, 2019 and 2018, respectively. As of December 31, 2020, the Company had total net operating loss carryforwards for federal income tax purposes of approximately $122.5 million. If not utilized, these net federal operating loss carryforwards will begin to expire at the end of the year. For tax years in January 1, 2018 onwards, any federal net operating losses generated will be allowable for carry forward indefinitely, as opposed to the original expiration of 20 years. As of December 31, 2020, the Company had $50.5 million of federal net operating losses that can be carryforward indefinitely. The Company also had a state net operating loss carryforward of approximately $90.3 million which will expire beginning in the year 2021. The Company also had federal and state research and development (“R&D”) tax credit carryforwards of approximately $2.8 million and $4.2 million, respectively. The federal tax R&D credit carryforwards will expire beginning in 2030 while the state tax R&D credit carryforwards have no expiration date. Utilization of the net operating loss carryforwards and R&D tax credit carryforwards may be subject to annual limitations due to the ownership change limitations provided by the Internal Revenue Code, as defined in Section 382, and other similar state provisions. The annual limitation may result in the expiration of net operating losses and credits before utilization. During the year ended December 31, 2018, the Company completed a formal 382 study for which the Company wrote off deferred tax assets for NOLs and credits of $3.1 million and $1.2 million, respectively. Since the Company had a full valuation allowance on these assets, there was no material impact to the tax provision. The Company completed another section 382 study for the year ended December 31, 2020 for which the Company had a change in ownership. No additional NOLs or credits will expire unused due to the 2020 annual limitation. Annually, the Company determines whether it is “more likely than not” that a tax position will be sustained upon examination by the appropriate taxing authorities in considering whether any tax benefit can be recorded in the consolidated financial statements. As of December 31, 2020, the Company had unrecognized tax benefits of approximately $8.2 million, none of which will affect the tax rate if recognized. It is unlikely that the amount of liability for unrecognized tax benefits will significantly change over the next 12 months. The following table summarizes the activity related to the Company’s gross unrecognized tax benefits (in thousands): Balance at December 31, 2017 $ 1,070 Additions for tax positions related to current year 57 Reductions for tax positions related to prior year (185) Balance at December 31, 2018 $ 942 Additions for tax positions related to current year 47 Additions for tax positions related to prior year — Balance at December 31, 2019 $ 989 Additions for tax positions related to current year 7,259 Additions for tax positions related to prior year — Balance at December 31, 2020 $ 8,248 It is the Company’s policy to include penalties and interest expense related to income taxes as part of the provision for income taxes. The Company’s major tax jurisdictions are the United States and California, Switzerland and Neuchâtel, and Grand Cayman. All of the Company’s tax years will remain open for examination by the federal and state tax authorities for three and four years, respectively, from the date of utilization of the net operating loss or R&D Credits. The Company does not have any tax audits or other issues pending.

Warrants for Convertible Prefer

Warrants for Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2020
Warrants and Rights Note Disclosure [Abstract]
Warrants for Convertible Preferred Stock	Warrants for Convertible Preferred Stock A summary of the outstanding convertible preferred stock warrants is as follows (in thousands, except per share and share amounts): December 31, 2019 Exercise Price Shares Fair Value of Liability Expiration Date Series C-1 convertible preferred stock warrants $ 10.57 215,291 $ — February 9, 2020 Series C-1 Convertible Preferred Stock Warrants In February 2018, warrants to purchase 7,884 shares of Series C-1 convertible preferred stock were exercised at an exercise price of $10.57 per share, yielding $0.1 million. Pursuant to the February 2018 warrant amendment, shares issuable upon exercise of the warrants decreased from 430,588 to 215,291. The Company revalued the remaining warrants at December 31, 2019 and December 31, 2018, and recorded income of less than $0.1 million and expense of less than $0.1 million, respectively, in change in other income (expense), net in the consolidated statements of operations and comprehensive loss for the years ended December 31, 2019 and 2018, respectively.

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2020
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock	Convertible Preferred Stock Under the Company’s Amended and Restated Certificate of Incorporation, the Company is authorized to issue 0 shares of convertible preferred stock. In April 2019, the Company issued 3,030,296 shares of Series G-1 convertible preferred stock at a price of $13.20 per share for cash proceeds of approximately $40.0 million. Additionally, the Company issued 1,903,935 shares of Series G-1 convertible preferred stock at a price of $13.20 per share upon the conversion of $25.1 million of convertible promissory notes and accrued interest with Boston Scientific Corporation (Note 6). Upon the closing of the IPO in October 2020, all outstanding shares of the convertible preferred stock converted into 17,797,026 shares of common stock and the related carrying value was reclassified to common stock and additional paid-in capital. There was no issued and outstanding convertible preferred stock as of December 31, 2020. As of December 31, 2019, convertible preferred stock consists of the following (in thousands, except per share and share amounts): Series Number of Shares Authorized Number of Shares Issued and Outstanding Carrying Value(1) Liquidation Preference per Share Liquidation Value Series A-1 8,486,224 848,595 $ 8,135 $ 9.59 $ 8,138 Series B-1 24,224,676 2,422,444 23,130 10.57 25,605 Series C-1 39,422,980 3,726,974 37,306 10.57 39,395 Series D-1 9,400,000 939,979 10,268 11.00 10,340 Series E-1 9,230,768 923,049 11,896 13.00 12,000 Series F-1 37,878,787 3,787,878 49,800 13.20 50,000 Series G-1 49,342,376 4,934,231 64,804 13.20 65,132 Total 177,985,811 17,583,150 $ 205,339 $ 210,610 _______________ (1) Carrying values above are net of issuance costs. Dividends The holders of Series A-1, Series B-1, Series C-1, Series D-1, Series E-1, Series F-1 and Series G-1 convertible preferred stock are entitled to receive dividends, out of any assets legally available, prior and in preference to any declaration or payment of any dividend on the common stock of the Company, at a rate of $0.7672, $0.8456, $0.8456, $0.88, $1.04, $1.056 and $1.056 respectively, per share per year (as adjusted for stock splits, stock dividends, reclassifications and similar events) payable quarterly when, and as declared by the Board of Directors and are not cumulative. After payment of such dividends, any additional dividends shall be distributed the holders of Series A-1, Series B-1, Series C-1, Series D-1, Series E-1, Series F-1 and Series G-1 convertible preferred stock and common stock on a pro rata basis. No dividends have been declared to date. Liquidation In the event of any liquidation, dissolution or winding up of the Company, either voluntary or involuntary, the holders of Series G-1 convertible preferred stock shall be entitled to receive, prior and in preference to any distribution of the assets of the Corporation or any such consideration to the holders of Series A-1, Series B-1, Series C-1, Series D-1, Series E-1 and Series F-1 convertible preferred stock or the holders of common stock, an amount equal to $13.20 per share (as adjusted for stock splits, stock dividends, reclassification and similar events) plus any declared but unpaid dividends. If upon the occurrence of such event, the assets and funds available are insufficient to permit the payment to the Series G-1 convertible preferred stockholders of the full preferential amounts, then the entire assets and funds of the Company legally available for distribution shall be distributed ratably among the holders of Series G-1 convertible preferred stock in proportion to the preferential amount each such holder is otherwise entitled to receive. After the payment in full of the Series G-1 liquidation preference, the holders of Series F-1 convertible preferred stock shall be entitled to receive, prior and in preference to any distribution of the assets of the Corporation or any such consideration to the holders of Series A-1, Series B-1, Series C-1, Series D-1 and Series E-1 convertible preferred stock or the holders of common stock, an amount equal to $13.20 per share (as adjusted for stock splits, stock dividends, reclassification and similar events) plus any declared but unpaid dividends. If upon the occurrence of such event, the assets and funds available are insufficient to permit the payment to the Series F-1 convertible preferred stockholders of the full preferential amounts, then the entire assets and funds of the Company legally available for distribution shall be distributed ratably among the holders of Series F-1 convertible preferred stock in proportion to the preferential amount each such holder is otherwise entitled to receive. After the payment in full of the Series F-1 liquidation preference, the holders of the Series E-1 convertible preferred stock shall be entitled to receive, prior and in preference to any distribution of the assets of the Corporation or any such consideration to the holders of Series A-1, Series B-1, Series C-1, and Series D-1 convertible preferred stock or the holders of common stock, an amount equal to $13.00 per share (as adjusted for stock splits, stock dividends, reclassification and similar events) plus any declared but unpaid dividends. If upon the occurrence of such event, after payment in full of the Series F-1 liquidation preference, the assets and funds available are insufficient to permit the payment to the Series E-1 convertible preferred stockholders of the full preferential amounts, then the entire assets and funds of the Company legally available for distribution shall be distributed ratably among the holders of Series E-1 convertible preferred stock in proportion to the preferential amount each such holder is otherwise entitled to receive. After the payment in full of the Series F-1 liquidation preference and the Series E-1 liquidation preference, the holders of Series A-1, Series B-1, Series C-1 and Series D-1 convertible preferred stock are entitled to receive, prior and in preference to any distribution of the assets of the Corporation or any such consideration to the holders of common stock, an amount equal to $9.59, $10.57, $10.57 and $11.00 per share (as adjusted for stock splits, stock dividends, reclassification and similar events) plus any declared but unpaid dividends. If upon the occurrence of such liquidation, the assets and funds of the Company legally available for distribution are insufficient to permit payment to such holders, then the entire remaining assets and funds shall be distributed ratably among such holders in proportion to the preferential amounts each such holder is otherwise entitled to receive. In the event of a Liquidation Transaction involving one or more third parties other than the purchaser of Series F-1 convertible preferred stock and after the payment in full of the liquidation preference required to be paid, the holders of the Series F-1 convertible preferred stock shall be entitled to receive, prior and in preference to any distribution of any of the assets of the Company or any such consideration to the holders of common stock an amount equal to the Additional Preference (as defined below) for each share of Series F-1 preferred stock then held by them. Upon the closing of a Liquidation Transaction, if the amounts earned or payable to the stockholders of the Corporation on or before the one (1) year anniversary of the closing of such Liquidation Transaction is (i) equal to or greater than $250.0 million but less than $300.0 million, the Additional Preference is equal to $3.30 per share (as adjusted for stock splits, stock dividends, reclassifications and the like) for each share of Series F-1 convertible preferred stock then held by them, (ii) equal to or greater than $300.0 million but less than $350.0 million, the Additional Preference is equal to $5.00 per share (as adjusted for stock splits, stock dividends, reclassifications and the like) for each share of Series F-1 preferred stock then held by them, and (iii) equal to or greater than $350.0 million, the Additional Preference is equal to $6.60 per share (as adjusted for stock splits, stock dividends, reclassifications and the like) for each share of Series F-1 convertible preferred stock then held by them. After liquidation preferences to the convertible preferred stockholders have been paid, and after the Additional Preference has been paid, if any, the remaining assets of the Company shall be distributed to the holders of common stock, Series A-1, Series B-1, Series C-1, Series D-1, Series E-1, Series F-1 and Series G-1 convertible preferred stock as if the convertible preferred shares were converted into common stock at then-applicable conversion price until the Series A-1, Series B-1, Series C-1, Series D-1, Series E-1, Series F-1 and Series G-1 convertible preferred stock have received an aggregate amount (including the initial preference amount) equal to $28.77, $31.71, $31.71, $33.00, $39.00, $39.60 and $39.60 per share (as adjusted for stock splits, stock dividends, reclassifications and similar events) plus any declared and unpaid dividends. The holders of common stock are entitled to receive ratably on a per-share basis all remaining assets. A liquidation, dissolution or winding up of the Company shall be deemed to be occasioned by, or include, (A) the sale, lease, license on an exclusive basis, conveyance or disposition (whether by merger or otherwise) by the Company of all or substantially all of the assets of the Company, or the sale or disposition of one or more subsidiaries of the Company if substantially all of the assets of the Company and its subsidiaries taken as a whole are held by such subsidiary or subsidiaries, or (B) the merger of the Company with or into any other corporation, limited liability company or other entity (other than a wholly-owned subsidiary of the Company); provided that none of the following shall be considered a Liquidation Transaction: (i) a merger effected exclusively for the purpose of changing the domicile of the Company, (ii) an equity financing effected for bona fide capital raising purposes in which the Company is the surviving entity or (iii) any transaction in which the stockholders of the Company immediately prior to the transaction own greater than 50% of the voting power of the Company or such other surviving or resulting entity (or if the Company or such other surviving or resulting entity is a wholly-owned subsidiary immediately following such acquisition, its parent). Voting The holders of convertible preferred stock shall have the same voting rights as the holders of common stock. The holders of common stock and the convertible preferred stock shall vote together as a single class on all matters. Each holder of common stock shall be entitled to one vote for each share of common stock held, and each holder of convertible preferred stock shall be entitled to the number of votes equal to the number of shares of common stock into which such shares of convertible preferred stock could be converted. As of December 31, 2020, the Board of Directors was comprised of seven members. For so long as there are outstanding at least 50,000 shares of Series A-1 convertible preferred stock (as adjusted for stock splits, reclassifications or similar events), the holders of Series A-1 convertible preferred stock, voting as a separate class, shall be entitled to elect one member of the Company’s Board of Directors. For so long as there are outstanding at least 50,000 shares of Series B-1 convertible preferred stock (as adjusted for stock splits, reclassifications or similar events), the holders of Series B-1 convertible preferred stock, voting as a separate class, shall also be entitled to elect two members of the Company’s Board of Directors. For so long as there are outstanding at least 50,000 shares of Series C-1 convertible preferred stock (as adjusted for stock splits, reclassifications or other similar transactions), the holders of Series C-1 convertible preferred stock, voting as a separate class, shall be entitled to elect two members of the Company’s Board of Directors. For so long as there are outstanding at least 50,000 shares of Series G-1 convertible preferred stock (as adjusted for stock splits, reclassifications or other similar transactions), the holders of Series G-1 convertible preferred stock, voting as a separate class, shall be entitled to elect one member of the Company’s Board of Directors. The holders of common stock and convertible preferred stock, voting together as a single class on an as-if-converted basis, shall be entitled to elect all remaining members of the Board of Directors. Conversion Each share of convertible preferred stock shall be convertible, at the option of the holder at any time after the date of issuance into the number of fully paid and non-assessable shares of common stock as determined by dividing the original issue price per share of each series of convertible preferred stock by the conversion price per share in effect for the shares of each series of convertible preferred stock at the time of conversion. The original conversion price per share of Series A-1, Series B-1, Series C-1, Series D-1, Series E-1, Series F-1 and Series G-1 convertible preferred stock shall be the original issue price, subject to adjustment, as described in the Company’s Amended and Restated Certificate of Incorporation. Each share of convertible preferred stock shall automatically be converted into shares of common stock at the conversion rate at the time in effect for such share immediately upon the earlier of (i) the Company’s sale of its common stock in a firm commitment underwritten public offering pursuant to a registration statement under the Securities Act of 1933 (“IPO”) which results in aggregate cash proceeds to the Company of not less than $30.0 million (net of underwriting discounts and commissions) (“Qualified IPO”) or (ii) the date specified by the vote or

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Stockholders' Deficit	Stockholders’ Equity (Deficit) Common Stock As of December 31, 2020 and December 31, 2019, the Company’s certificate of incorporation authorized the Company to issue up to 200,000,000 and 240,000,000 shares of common stock, respectively. Common stockholders are entitled to dividends as and when declared by the Board of Directors, subject to the rights of holders of all classes of stock outstanding having priority rights as to dividends. There have been no dividends declared to date. The holder of each share of common stock is entitled to one vote. The Company constructively retired 414 shares of common stock during the year that were abandoned. Shares Reserved for Future Issuance The Company has reserved shares of common stock for future issuances as follows: December 31, 2020 2019 Series A-1 convertible preferred stock outstanding — 848,595 Series B-1 convertible preferred stock outstanding — 2,422,444 Series C-1 convertible preferred stock outstanding — 3,726,974 Series D-1 convertible preferred stock outstanding — 939,979 Series E-1 convertible preferred stock outstanding — 923,049 Series F-1 convertible preferred stock outstanding — 3,787,878 Series G-1 convertible preferred stock outstanding — 4,934,231 Warrants to purchase Series C-1 convertible preferred stock — 215,291 Common stock options issued and outstanding 2,923,403 3,279,324 Common stock available for future grants 3,233,794 77,603 Common stock available for ESPP 720,000 — Total 6,877,197 21,155,368 Stock Option Plan As of December 31, 2020, the Company reserved 9,842,151 shares of its common stock under its 2000 Stock Plan (the “2000 Stock Plan”), the 2010 Stock Plan (the “2010 Stock Plan”), the 2020 Stock Plan (the “2020 Stock Plan”), and the 2020 Equity Incentive Plan (the “2020 Equity Incentive Plan” and, together with the 2000 Stock Plan, the 2010 Stock Plan and the 2020 Stock Plan, the “Stock Plans”). Options granted under the Stock Plans may be either incentive stock options or nonqualified stock options. Incentive stock options (“ISO”) may be granted only to the Company employees (including officers and directors). Nonqualified stock options (“NSO”) may be granted to the Company employees and consultants. As of December 31, 2020 and December 31, 2019, no shares of common stock remain available for issuance to officers, directors, employees and consultants pursuant to the 2000 Stock Plan. Options to purchase the Company’s common stock may be granted at a price not less than 100% of the fair market value in the case of ISO or NSO, except for an employee or non-employee with options who owns more than 10% of the voting power of all classes of stock of the Company in which case the exercise price shall be no less than 110% of the fair market value per share on the grant date. Fair market value is determined by the Board of Directors. Options are immediately exercisable and vest as determined by the Board of Directors ranging from immediately upon grant to a rate of 25% per annum over four years from the grant date. Options expire as determined by the Board of Directors but not more than ten years after the date of grant. Activity under the Stock Plans is set forth below: Outstanding Options Shares Available for Grant Number of Shares Weighted Average Exercise Price Balance, January 1, 2018 125,199 2,419,948 $ 1.52 Additional shares reserved 502,179 — $ — Options granted (255,900) 255,900 $ 1.37 Options exercised — (18,153) $ 1.68 Options canceled (1) 11,201 (31,201) $ 1.53 Balance, December 31, 2018 382,679 2,626,494 $ 1.51 Additional shares reserved 738,572 — — Options granted (1,078,957) 1,078,957 1.93 Options exercised — (390,318) 1.35 Options canceled (1) 35,309 (35,809) 1.39 Balance, December 31, 2019 77,603 3,279,324 $ 1.66 Additional shares reserved 4,553,378 — — Options granted (1,466,071) 1,466,071 7.73 Options exercised — (1,745,040) 1.55 Options canceled (1) 68,884 (76,952) 3.55 Balance, December 31, 2020 3,233,794 2,923,403 $ 4.72 ______________ (1) Canceled stock options issued under the Company’s 2000 Stock Plan were canceled after the 2010 Stock Plan was approved and are not included in the shares available for grant as they were not returned to the stock option pool. The aggregate intrinsic value of options exercised during the years ended December 31, 2020, December 31, 2019 and December 31, 2018 was $2.0 million, $0.2 million and less than $0.1 million, respectively. The weighted average exercise price and aggregate intrinsic value of options outstanding at December 31, 2020 was $4.72 per share and $188.0 million, respectively. The weighted average exercise price and aggregate intrinsic value of options outstanding at December 31, 2019 was $1.66 per share and $10.9 million, respectively. The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying stock options and the fair value of the Company’s common stock for stock options that were in-the-money as of December 31, 2020 and December 31, 2019. December 31, 2020 Number of Shares Weighted Average Exercise Price Weighted Average Contractual Life (in Years) Options vested 1,219,241 $ 2.03 5.23 Options vested and expected to vest 2,923,403 $ 4.72 7.63 Total intrinsic value of options vested as of December 31, 2020 and December 31, 2019 was $81.7 million and $7.6 million, respectively. Early Exercise of Stock Options Under the terms of the individual option grants, all options are fully exercisable on the grant date, subject to the Company’s repurchase right at the original exercise price. Accordingly, options may be exercised prior to vesting. The shares are subject to the Company’s lapsing repurchase right upon termination of employment or over the options’ vesting period of generally four years at the original purchase price. The proceeds initially are recorded in other liabilities from the early exercise of stock options and are reclassified to additional paid-in capital as the Company’s repurchase right lapses. During the year ended December 31, 2020 and 2019, the Company repurchased 10,000 and 9,147 shares of common stock for less than $0.1 million and less than $0.1 million, respectively. As of December 31, 2020 and December 31, 2019, 355,677 and 199,810 shares were subject to repurchase, with an aggregate exercise price of $0.6 million and $0.3 million, respectively, and were recorded in other current liabilities. Stock-Based Compensation for Employees and Non-Employees During the years ended December 31, 2020, December 31, 2019 and December 31, 2018, the Company granted stock options to employees and non-employees to purchase 1,466,071, 1,078,957 and 255,900 shares of common stock, respectively. The weighted average grant-date fair value of the stock options granted during the years ended December 31, 2020, December 31, 2019 and December 31, 2018 was $3.78, $1.79 and $0.70 per share, respectively. The Company uses the Black-Scholes Merton option-pricing model to determine the fair value of stock options. The determination of the fair value of stock-based payment awards on the date of grant is affected by the stock price as well as assumptions regarding a number of complex and subjective variables. These variables include expected stock price volatility over the term of the awards, actual and projected employee stock option exercise behaviors, risk-free interest rates and expected dividends. The estimated grant date fair values of employee stock options were calculated using the following assumptions: Years Ended December 31, 2020 2019 2018 Weighted average expected term (in years) 5.0 - 6.1 5.3 - 6.1 6.3 Volatility 40.0% - 44.7% 47.1% - 49.7% 46.0% Risk-free interest rate 0.2% - 1.7% 1.4% - 1.8% 2.4%-2.9% Dividend yield — — — Expected Term The expected term is calculated using the simplified method, which is available where there is insufficient historical data about exercise patterns and post-vesting employment termination behavior. The simplified method is based on the vesting period and the contractual term for each grant, or for each vesting-tranche for awards with graded vesting. The mid-point between the vesting date and the maximum contractual expiration date is used as the expected term under this method. For awards with multiple vesting-tranches, the periods from grant until the mid-point for each of the tranches are averaged to provide an overall expected term. Volatility The expected stock price volatility assumptions for the Company’s stock options for the years ended December 31, 2020, December 31, 2019 and December 31, 2018 was determined by examining the historical volatilities for industry peers, referred to as “guideline” companies, as the Company did not have any trading history for the Company’s common stock. In evaluating similarity, the Company considered factors such as industry, stage of life cycle and size. Risk-Free Rate The risk-free interest rate assumption is based on the U.S. Treasury instruments whose term was consistent with the expected term of the Company’s stock options. Dividend Yield The expected dividend assumption is based on the Company’s history and expectation of dividend payouts. Fair Value of Common Stock Prior to the IPO the fair value of the Company’s common stock is determined by the board of directors with assistance from management and, in part, on input from an independent third-party valuation firm. The board of directors determines the fair value of common stock by considering a number of objective and subjective factors, including valuations of comparable companies, sales of convertible preferred stock, operating and financial performance, the lack of liquidity of the Company’s common stock and the general and industry-specific economic outlook. Subsequent to the Company’s IPO, the fair value of the Company’s common stock is determined based on its closing market price. 2020 Employee Share Purchase Plan In September 2020, the Company adopted the 2020 Employee Share Purchase Plan (“ESPP”), which became effective on the business day prior to the effectiveness of the registration statement relating to the IPO. A total of 720,000 shares of common stock were initially reserved for issuance under the ESPP. The ESPP permits eligible employees to acquire shares of the Company’s common stock through periodic payroll deductions of up to 15% of base compensation. No employee may purchase more than 2,500 shares during an offering period. In addition, no employee may purchase more than $25,000 worth of stock, determined by the fair market value of the shares at the time such option is granted, in one calendar year. The ESPP provides for an offering period from September 30, 2020 until May 24, 2021 with the purchase date of last date of offering period. At the end of each purchase period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last trading day of the offering period. The Company issued no shares under the ESPP for the year ended December 31, 2020. Shares authorized for future purchase under the ESPP were 720,000 at December 31, 2020. In January 2021, the number of shares of common stock available for issuance under the ESPP was increased by 356,937 shares as a result of the automatic increase provision in the ESPP. Compensation expense is calculated using the fair value of the employees' purchase rights under the Black-Scholes model. Year Ended December 31, 2020 Weighted average expected term (in years) 0.6 Volatility 67.7% - 68.2% Risk-free interest rate 0.1% Dividend yield — Total Stock-Based Compensation Stock-based compensation expense is reflected in the statements of operations and comprehensive loss as follows (in thousands): Years Ended December 31, 2020 2019 2018 Cost of goods sold $ 39 $ 30 $ 18 Research and development 398 64 62 Selling, general and administrative 2,760 270 286 Total $ 3,197 $ 364 $ 366 The above stock-based compensation expense related to the following equity-based awards: Years Ended December 31, 2020 2019 2018 Stock options $ 2,055 $ 364 $ 366 ESPP 1,142 — — Total $ 3,197 $ 364 $ 366 Stock-based compensation of $0.3 million, $0 and $0 was capitalized into inventory for the years ended December 31, 2020, 2019, and 2018, respectively. Capitalized stock-based compensation is recognized as cost of sales when the related product is sold. As of December 31, 2020, there was $14.8 million of unrecognized compensation costs related to non-vested common stock options, expected to be recognized over a weighted-average period of 2.28 years, respectively. The total grant date fair value of shares vested during the years ended December 31, 2020, December 31, 2019 and December 31, 2018 was $1.9 million, $0.3 million and $0.4 million, respectively. As of December 31, 2020, the Company had unrecognized employee stock-based compensation relating to ESPP awards of approximately $2.3 million, which is expected to be recognized over a weighted-average period of 0.4 years.

Net Loss per Share Attributable

Net Loss per Share Attributable to Common Stockholders	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Net Loss per Share Attributable to Common Stockholders	Net Loss per Share Attributable to Common Stockholders The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders which excludes shares which are legally outstanding, but subject to repurchase by the Company (in thousands, except share and per share amounts): Years Ended December 31, 2020 2019 2018 Numerator Net loss attributable to common stockholders $ (32,231) $ (20,703) $ (18,479) Denominator Weighted-average common stock outstanding 10,341,809 1,796,233 1,706,654 Less: weighted-average common shares subject to repurchase (156,968) (20,123) (31,875) Weighted-average common shares used to compute basic and diluted net loss per share 10,184,841 1,776,110 1,674,779 Net loss per share attributable to common stockholders, basic and diluted $ (3.16) $ (11.66) $ (11.03) The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted average shares outstanding because such securities have an antidilutive impact due to the Company’s net loss, in common stock equivalent shares: Years Ended December 31, 2020 2019 2018 Convertible preferred stock — 17,583,150 12,648,919 Convertible preferred stock warrants — 215,291 215,291 Options to purchase common stock 2,923,403 3,279,324 2,626,494 Unvested early exercised common stock options 355,677 199,810 26,852 Shares committed under ESPP 47,174 — — Conversion of convertible notes* — — — ______________ * At December 31, 2018, the conversion of the convertible notes into convertible preferred stock was dependent on the outstanding loan balance including accrued interest and the conversion stock per share price at the date of Qualified Equity Financing, Change of Control, Liquidation, or Prepayment Conversion (see Note 6). These factors were not estimable and the number of convertible preferred stock was not determinable. These convertible notes converted to Series G-1 convertible preferred in April 2019 (Note 10).

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Segment Information	Segment InformationThe chief operating decision maker for the Company is the Chief Executive Officer. The Company’s Chief Executive Officer reviews financial information presented on a consolidated basis, accompanied by information about revenue by geographic region, for purposes of allocating resources and evaluating financial performance. The Company has one business activity and there are no segment managers who are held accountable for operations, operating results or plans for levels or components below the consolidated unit level. Accordingly, the Company has determined that it has a single reportable and operating segment structure. The Company’s Chief Executive Officer evaluates performance based primarily on revenue in the geographic locations in which the Company operates. Revenue by geographic area is based on the billing address of the customer. The following table sets forth our revenue by geographic area (in thousands): Year Ended December 31, 2020 2019 2018 United States $ 16,189 $ 10,704 $ 563 Europe, Middle-East and Africa 13,808 18,364 16,175 Asia Pacific 2,687 3,227 3,115 Other International 49 300 151 Total $ 32,733 $ 32,595 $ 20,004 Revenue from Germany represented 17%, 22%, and 37% of total revenue for the years ended December 31, 2020, 2019, and 2018, respectively. Long-lived assets by geographic area are based on physical location of those assets. The following table sets forth our long-lived assets by geographic area (in thousands): December 31, 2020 2019 United States $ 1,437 $ 852 Europe, Middle-East and Africa 29 40 Asia Pacific 8 10 Total $ 1,474 $ 902

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit PlanEffective October 1997, the Company implemented a retirement savings plan (the “Savings Plan”) which is intended to qualify as a deferred savings plan under Section 401(k) of the Internal Revenue Code. Participants are allowed to contribute up to 100% of the total compensation, not to exceed the amount allowed by the applicable statutory prescribed limit. There have been no contributions made to the Savings Plan by the Company since inception.

Related Parties

Related Parties	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Parties	Related PartiesSince October 2013, the Company has received services from the chairman of a subsidiary of the Company. During 2014, this person served as Interim CEO and was appointed to the Board of Directors of the Company. Amounts paid related to consulting services for the years ended December 31, 2020, December 31, 2019 and December 31, 2018 was less than $0.1 million, $0.1 million and $0.1 million, respectively.See Note 6 for details regarding the Company’s Second Lien Loan and Security Agreement with Boston Scientific Corporation.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Selected Quarterly Financial Data (unaudited)	Selected Quarterly Financial Data (unaudited)The following table provides the selected quarterly financial information for the years 2020 and 2019 (in thousands, except per share data): Three months ended March 31, 2020 June 30, 2020 September 30, 2020 December 31, 2020 Revenue $ 8,618 $ 3,673 $ 10,612 $ 9,830 Gross profit $ 5,650 $ 1,012 $ 7,462 $ 7,078 Net loss $ (7,163) $ (11,911) $ (3,860) $ (9,297) Net loss per share attributable to common $ (3.76) $ (6.15) $ (1.37) $ (0.27) Three months ended March 31, 2019 June 30, 2019 September 30, 2019 December 31, 2019 Revenue $ 5,778 $ 7,366 $ 9,104 $ 10,347 Gross profit $ 3,717 $ 4,953 $ 6,407 $ 7,337 Net loss $ (6,128) $ (5,571) $ (4,335) $ (4,669) Net loss per share attributable to common $ (3.61) $ (3.24) $ (2.41) $ (2.48)

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsSubsequent to December 31, 2020, the Company granted 6,300 restricted stock units and options to purchase 8,600 shares of common stock to employees, subject to service-based vesting conditions. The options have a weighted-average exercise price of $62.34 per share.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared using accounting principles generally accepted in the United States of America (“GAAP”).
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Significant estimates and assumptions include reserves and write-downs related to inventories, the recoverability of long term assets, valuation of equity instruments and equity-linked instruments, valuation of common stock, stock-based compensation, valuation of the convertible preferred stock warrant liability and derivative liabilities, intangible assets, goodwill, debt and related features, deferred tax assets and related valuation allowances and impact of contingencies.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of the Company’s financial instruments consisting of cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate fair value due to their relatively short maturities. The convertible preferred stock warrant liability and derivative liabilities were carried at fair value based on unobservable market inputs. Based on the borrowing rates currently available to the Company for debt with similar terms and consideration of default and credit risk, the carrying value of the term loan and convertible note
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the time of purchase to be cash equivalents, which include money market funds.
Restricted Cash	Restricted Cash Restricted cash is comprised of cash that is restricted as to withdrawal or use under the terms of certain contractual agreements. Restricted cash for years ended December 31, 2020 consists of collateral for letters of credit issued in connection with the real estate lease in Redwood City, California.
Short-Term Marketable Securities	Short-Term Marketable SecuritiesThe Company determines the appropriate classification of its investments in marketable securities at the time of purchase and reevaluates such designation at each balance sheet date. The Company has classified and accounted for its marketable securities as available-for-sale. After consideration of the Company’s risk versus reward objectives and liquidity requirements, the Company may sell these securities prior to their stated maturities. As the Company views these securities as available to support current operations, the Company classifies highly liquid securities with original maturities greater than three months at the time of purchase as short-term marketable securities on the balance sheet. These securities are carried at fair value as determined based upon quoted market prices or pricing models for similar securities. Unrealized gains and losses on available for sale debt securities, if any, are excluded from earnings and are reported as a component of accumulated other comprehensive income (loss). The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity, which is included in interest income on the statements of operations and comprehensive loss. Realized gains and losses, if any, on available-for-sale securities are included in other income (expense), net. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of risk consist principally of cash, cash equivalents and accounts receivable. The Company maintains its cash and cash equivalents balances with established financial institutions and, at times, such balances with any one financial institution may be in excess of the Federal Deposit Insurance Corporation (“FDIC”) insured limits. As of December 31, 2020 and 2019, the Company also had cash on deposit with foreign banks of approximately $5.6 million and $5.2 million, respectively, that was not federally insured. The Company earns revenue from the sale of its products to distributors and other customers such as hospitals. Sales of Zephyr Valves and delivery catheters accounted for most of our revenue for the years ended December 31, 2020, 2019 and 2018. The Company’s accounts receivable are derived from revenue earned from distributors and customers. The Company performs ongoing credit evaluations of its customers’ and distributors’ financial condition and generally requires no collateral from its customers and distributors. At December 31, 2020 and 2019, no customer or distributor accounted for more than 10% of accounts receivable. For the years ended December 31, 2020, 2019 and 2018, no customer or distributor accounted for more than 10% of revenue. The Company relies on single source suppliers for the components, sub-assemblies and materials for its products. These components, sub-assemblies and materials are critical and there are no or relatively few alternative sources of supply. The Company’s suppliers have generally met the Company’s demand for their products and services on a timely basis in the past.
Deferred Offering Costs	Deferred Offering CostsDeferred offering costs, consisting of legal, accounting and other fees and costs relating to the Company’s IPO, are capitalized and recorded on the balance sheet. As of December 31, 2019, $1.6 million of deferred offering costs were recorded on the consolidated balance sheet.In connection with the IPO, all deferred offering costs incurred after May 2020 were recorded as reduction of the gross proceeds from the IPO in the additional paid-in capital on the accompanying balance sheet as of December 31, 2020.
Accounts Receivable and Allowances	Accounts Receivable and AllowancesAccounts receivable are recorded at the amounts billed less estimated allowances for doubtful accounts. The Company continually monitors customer payments and maintains an allowance for estimated losses resulting from a customer’s inability to make required payments. Company considers factors such as historical experience, credit quality, age of the accounts receivable balances, geographic related risks and economic conditions that may affect a customer’s ability to pay.
Inventories	InventoriesInventories are valued at the lower of cost to purchase or manufacture the inventory or net realizable value. Cost is determined using the first-in, first-out method (“FIFO”) for all inventories. Net realizable value is determined as the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The Company records write-downs of inventories which are obsolete or in excess of anticipated demand or market value based on consideration of product lifecycle stage, technology trends, product development plans and assumptions about future demand and market conditions. Inventory write-downs reduce the carrying value of inventory to its net realizable value.
Property and Equipment, Net	Property and Equipment, NetProperty and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the assets, generally between three
Impairment of Long-lived Assets	Impairment of Long-lived Assets The Company evaluates its long-lived assets for indicators of possible impairment by comparison of the carrying amounts to future net undiscounted cash flows expected to be generated by such assets when events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. Should an impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over the asset’s fair value or discounted estimates of future cash flows. The Company has not identified any such impairment losses to date.
Goodwill	Goodwill Goodwill represents the excess of the purchase price over the fair value of net tangible and identified intangible assets acquired in a business combination. Goodwill is not amortized but is evaluated at least annually for impairment or when a change in facts and circumstances indicate that the fair value of the goodwill may be below its carrying value.
Intangible Assets	Intangible Assets Intangible assets consist of developed technology and trademarks. Intangible assets were recorded at their fair values at the date of acquisition and are amortized using the straight-line method over a 15-year useful life (Note 5).
Leases	Leases The Company leases its facilities and vehicles and meets the requirements to account for these leases as operating leases. The Company recognizes rent expense on a straight-line basis over the non-cancelable lease term. Where leases contain escalation clauses, rent abatements or concessions, such as rent holidays and landlord or tenant incentives or allowances, the Company applies them in the determination of straight-line rent expense over the lease term. Upon adoption of ASC 842, Leases, on January 1, 2019, the Company determined if an arrangement is a lease, or contains a lease, at inception. The asset component of the Company’s operating leases is recorded as right-of-use assets, and the liability component is recorded as current lease liabilities and long-term lease liabilities in the Company’s consolidated balance sheets. As of December 31, 2020 and 2019, the Company did not record any finance leases. ROU assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate, which is the estimated rate the Company would be required to pay for a fully collateralized borrowing equal to the total lease payments over the term of the lease, to determine the present value of future minimum lease payments. The ROU asset also includes any lease payments made to the lessor at or before the commencement date, minus lease incentives received, and initial direct costs incurred. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. For lease agreements entered into or reassessed after the adoption of ASC 842, the Company combines lease and non-lease components. Variable lease payments are expenses as incurred. Assumptions made by the Company at the commencement date are re-evaluated upon occurrence of certain events, including a lease modification. A lease modification results in a separate contract when the modification grants the lessee an additional right of use not included in the original lease and when lease payments increase commensurate with the standalone price for the additional right of use. When a lease modification results in a separate contract, it is accounted for in the same manner as a new lease.
Convertible Preferred Stock	Convertible Preferred Stock The Company recorded all shares of convertible preferred stock at their respective fair values on the dates of issuance, net of issuance costs. The convertible preferred stock was recorded outside of permanent equity because while it is not mandatorily redeemable, in certain events considered not solely within the Company’s control, such as a merger, acquisition or sale of all or substantially all of the Company’s assets (each, a “deemed liquidation event”), the convertible preferred stock would become redeemable at the option of the holders of at least a majority of the then outstanding such shares. The Company had not adjusted the carrying values of the convertible preferred stock to its liquidation preference because a deemed liquidation event obligating the Company to pay the liquidation preferences to holders of shares of convertible preferred stock was not probable. Subsequent adjustments to the carrying values to the liquidation preferences would be made only when it became probable that such a deemed liquidation event would occur. All outstanding shares of the convertible preferred stock converted into common stock upon effectiveness of the IPO.
Convertible Preferred Stock Warrants	Convertible Preferred Stock Warrants The Company’s convertible preferred stock warrants required liability classification and accounting as the underlying convertible preferred stock was considered contingently redeemable and might obligate the Company to transfer assets to the holders at a future date upon occurrence of a deemed liquidation event. The convertible preferred stock warrants were recorded at fair value upon issuance and were subject to remeasurement to fair value at each balance sheet date, with any changes in fair value recognized in the consolidated statements of operations and comprehensive loss. The Company continued to adjust the convertible preferred stock warrant liability for changes in fair value until the earlier of the exercise or expiration of the convertible preferred stock warrants, occurrence of a deemed liquidation event or conversion of convertible preferred stock into common stock.
Revenue Recognition	Revenue Recognition The Company’s revenue is generated from the sale of its products to distributors and hospitals in the United States and international markets. Under ASC 606, revenue is recognized when the customer obtains controls of promised goods or services, in an amount that reflects consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, the Company performs the following five steps as prescribed by ASC 606: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies performance obligations. A contract with a customer exists when (i) the Company enters into a legally enforceable contract with a customer that defines each party’s rights regarding the products or services to be transferred and identifies the payment terms related to these products or services, (ii) the contract has commercial substance and, (iii) the Company determines that collection of substantially all consideration for products or services that are transferred is probable based on the customer’s intent and ability to pay the promised consideration. The Company identifies performance obligations in contracts with customers, which may include its products and implied promises to provide free products and analysis services for patient scans. The transaction price is determined based on the amount expected to be entitled to in exchange for transferring the promised services or product to the customer. The Company is entitled to the total consideration for the products ordered by customers, net of early pay discounts, volume rebate adjustments and other transaction price adjustments. The Company’s payment terms to customers generally range from 30 to 60 days. Payment terms fall within the one-year guidance for the practical expedient which allows the Company to forgo adjustment of the promised amount of consideration for the effects of a significant financing component. The Company excludes taxes assessed by governmental authorities on revenue-producing transactions from the measurement of the transaction price. Assuming all other revenue recognition criteria are met, revenue is recognized when control of the Company’s products transfers to the customer. For sales where the Company’s sales representative hand delivers product directly to the hospital or medical center control transfers to the customer upon this delivery. For sales where products are shipped, control is transferred either upon shipment or delivery of the products to the customer, depending on the shipping terms and conditions. For consignment sales, control is transferred when the products are used by the customer in procedures. The Company defers revenue relating to any remaining performance obligations by the Company to the customer after delivery, such as free products and free analysis services of patient scans to determine suitability of the patients for the treatment using the Company’s Zephyr Valves. As permitted under the practical expedient, the Company does not disclose the value of unsatisfied performance obligations for contracts with an original expected length of one year or less. The Company accepts product returns at its discretion or if the product is defective as manufactured. Historically, the actual product returns have been immaterial to the Company’s financial statements. The Company elected to treat shipping and handling costs as a fulfillment cost and include them in the cost of goods sold as incurred. In those cases where the Company bills shipping and handling costs to customers, it will classify the amounts billed within revenue. The Company disaggregates its revenue by major geographic region, which has been disclosed in Note 13, “Segment Information”. The Company’s contract liabilities consist of deferred revenue for remaining performance obligations by the Company to the customer after delivery, which was $0.1 million and $0.2 million as of December 31, 2020 and December 31, 2019. The deferred revenue as of December 31, 2018 was $0.1 million, which was recognized as revenue during the year ended December 31, 2019. The deferred revenue as of December 31, 2019 of $0.2 million, which was recognized as revenue during the year ended December 31, 2020. Costs associated with product sales include commissions. The Company applies the practical expedient and recognizes commissions as expense when incurred because the expense is incurred at a point in time and the amortization period is less than one year. Commissions are recorded as selling expense.
Cost of Goods Sold	Cost of Goods Sold The Company manufactures certain products at its facility and purchases other products from third party manufacturers. Cost of goods sold consists primarily of costs related to materials, components and subassemblies, third-party costs, manufacturing overhead costs, direct labor, reserves for excess, obsolete and non-sellable inventories as well as distribution-related expenses. A significant portion of the Company’s cost of goods sold currently consists of manufacturing overhead costs. These overhead costs include the cost of quality assurance,
Research and Development	Research and Development Research and development expenses consist of compensation costs, stock-based compensation, engineering and research expenses, clinical trials and related expenses, regulatory expenses, manufacturing expenses incurred to build products for testing, allocated facilities costs, consulting fees and other expenses incurred to sustain the Company’s overall research and development programs. All research and development costs are expensed as incurred. Clinical trial costs are a significant component of the Company’s research and development expenses. The Company has a history of contracting with third parties that perform various clinical trial activities on the Company’s behalf in the ongoing development of its product candidates. The financial terms of these contracts are subject to negotiations and may vary from contract to contract and may result in uneven payment flow. The Company accrues and expenses costs for its clinical trial activities performed by third parties, including clinical research organizations and other service providers, based upon estimates of the work completed over the life of the individual study in accordance with associated agreements. The Company determines these estimates through discussion with internal personnel and outside service providers as to progress or stage of completion of trials or services pursuant to contracts with clinical research organizations and other service providers and the agreed-upon fee to be paid for such services.
Advertising Costs	Advertising CostsThe Company expenses the costs of advertising as incurred.
Foreign Currency Translation and Transaction Gains and Losses	Foreign Currency Translation and Transaction Gains and Losses The functional currencies of the Company’s wholly owned subsidiaries in the Cayman Islands and the Netherlands are the U.S. dollar. The functional currencies of the Company’s wholly owned subsidiaries in Switzerland, Germany, Australia, the United Kingdom, France and Hong Kong are the Swiss franc. The functional currency of the Company’s subsidiary in Italy is the Euro. Accordingly, asset and liability accounts of Switzerland, Germany, Australia, the United Kingdom, Italy and Hong Kong operations are translated into U.S. dollars using the current exchange rate in effect at the balance sheet date and equity accounts are translated into U.S. dollars using historical rates. The revenues and expenses are translated using the average exchange rates in effect during the period, and gains and losses from foreign currency translation adjustments are included as a component of accumulated other comprehensive income in the consolidated balance sheet. Foreign currency translation adjustments are recorded in other comprehensive income (loss) in the consolidated statements of operations and comprehensive loss and was $0.3 million, less than $0.1 million and $0.1 million during the years ended December 31, 2020, 2019 and 2018, respectively.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation arrangements with employees and non-employees in accordance with ASC 718, Compensation—Stock Compensation , using a fair-value based method. The Company determines the fair value of all stock options and ESPP awards on the date of grant using the Black-Scholes option pricing model. The Company’s determination of the fair value is impacted by its common stock price as well as assumptions regarding a number of complex and subjective variables. These variables include, but are not limited to, the expected term that options will remain outstanding, expected common stock price volatility over the term of the option awards, risk-free interest rates and expected dividends. Changes in the assumptions can materially affect the fair value and ultimately how much stock-based compensation expense is recognized. These inputs are subjective and generally require significant analysis and judgment to develop. The fair value of time-based awards is recognized over the period during which an option holder is required to provide services in exchange for the option award, known as the requisite service period, which is typically the vesting period using the straight-line method. The fair value of performance-based awards is recognized over the requisite service period using the graded vesting method. The Company accounts for forfeitures as they occur. The Company issued stock options in exchange for the receipt of goods or services from non-employees. Costs for such equity instruments are measured at the fair value of the equity instruments issued on the measurement date as the Company believes that the fair value of the equity instrument is more reliably measured than the fair value of the services received. Up to December 31, 2018, the value of equity instruments issued to non-employees was determined on the earlier of the date on which there first existed a firm commitment for performance by the provider of goods and services or on the date performance is complete, using the Black-Scholes option pricing model. Therefore, the measurement of stock-based compensation issued to non-employees was subject to periodic adjustment as the underlying equity instruments vested. Stock-based compensation expense related to stock options granted to non-employees was recognized as the stock options are earned. Upon adoption of ASU 2018-07 for the periods after January 1, 2019, the Company accounts for shared-based awards granted to non-employees based on the fair value on the date of grant and recognizes compensation expense for those awards over the requisite service period, which is generally the vesting period of the respective award.
Fair Value of Common Stock	Fair Value of Common Stock Prior to the Company’s IPO, the fair value of the Company’s common stock was determined by the board of directors with assistance from management and external appraisers. Management’s approach to estimate the fair value of the Company’s common stock was consistent with the methods outlined in the American Institute of Certified Public Accountants’ Practice Aid, Valuation of Privately-Held-Company Equity Securities Issued as Compensation (“Practice Aid”). Management considered several factors to estimate enterprise value, including significant milestones that would generally contribute to increases in the value of the common stock. Subsequent to the Company’s IPO, the fair value of the Company’s common stock is determined based on its closing market price.
Income Taxes	Income Taxes The Company accounts for income taxes under the asset and liability method, whereby deferred tax assets and liabilities are determined based on the difference between the consolidated financial statements and tax bases of assets and liabilities using the enacted tax rates in effect for the year in which the differences are expected to affect taxable income. A valuation allowance is established when necessary to reduce deferred tax assets when management estimates, based on available objective evidence, that it is more likely than not that the benefit will not be realized for the deferred tax assets. The Company also follows the provisions of ASC 740-10, Accounting for Uncertainty in Income Taxes . ASC 740-10 prescribes a comprehensive model for the recognition, measurement, presentation and disclosure in financial statements of any uncertain tax positions that have been taken or expected to be taken on a tax return. No liability related to uncertain tax positions is recorded on the consolidated financial statements. It is the Company’s policy to include penalties and interest expense related to income taxes as part of the provision for income taxes.
Net Loss per Share Attributable to Common Stockholders	Net Loss per Share Attributable to Common Stockholders Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common stock and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, convertible preferred stock, stock options,
Comprehensive Loss	Comprehensive Loss The Company is required to report all components of comprehensive loss, including net loss, in the financial statements in the period in which they are recognized. Comprehensive loss is defined as a change in equity of a business enterprise during a period, resulting from transactions and other events and circumstances from non-owner sources. The Company’s currency translation adjustment and unrealized gains and losses from marketable securities are the components of other comprehensive loss that are excluded from the reported net loss for all periods presented.
Recently Adopted Accounting Pronouncements and Recent Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Pronouncements In August 2018, FASB issued ASU 2018-13, Fair Value Measurement (Topic 820), Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement . This ASU amends the disclosure requirement in ASC 820, Fair Value Measurement , by adding, changing or removing certain disclosures. This ASU applies to all entities that are required under this guidance to provide disclosure about recurring or nonrecurring fair value measurements. The amendments require new disclosures related to: changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period; range and weighted-average of significant unobservable inputs used to develop Level 3 fair value measurements. In addition, there are certain changes in disclosure requirements in the existing guidance. For all entities, this ASU is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted. The Company adopted ASU 2018-13 as of January 1, 2020 and the adoption had no material impact on the Company’s consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, Intangibles – Goodwill and Other: Simplifying the Test for Goodwill Impairment . The amendments eliminate Step 2 from the goodwill impairment test. The annual, or interim, goodwill impairment test is performed by comparing the fair value of a reporting unit with its carrying amount. An impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. In addition, income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit should be considered when measuring the goodwill impairment loss, if applicable. The amendments also eliminate the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails that qualitative test, to perform Step 2 of the goodwill impairment test. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. This ASU is effective for public business entities for its annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted. The Company adopted ASU 2017-04 as of January 1, 2020 and the adoption had no material impact on the Company’s consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848) (“ASU 2020-04”). The amendments in ASU 2020-04 provide optional expedients and exceptions for applying generally accepted accounting principles to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. The amendments in ASU 2020-04 are effective for all entities as of March 12, 2020 through December 31, 2022. An entity may elect to apply the amendments for contract modifications by Topic or Industry Subtopic as of any date from the beginning an interim period that includes or is subsequent to March 12, 2020, or prospectively from the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic, the amendments must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The Company may elect to apply ASU 2020-04 as its contracts referenced in London Interbank Offered Rate (“LIBOR”) are impacted by reference rate reform. The Company is currently evaluating the impact of the adoption of this ASU on the Company’s consolidated financial statements. In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity's Own Equity (Subtopic 815-40)—Accounting For Convertible Instruments and Contracts in an Entity's Own Equity (“ASU 2020-06”). ASU 2020-06 simplifies accounting for convertible instruments by removing major separation models required under current GAAP. Consequently, more convertible debt instruments will be reported as a single liability instrument with no separate accounting for embedded conversion features. ASU 2020-06 removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception, which will permit more equity contracts to qualify for it. ASU 2020-06 also simplifies the diluted net income per share calculation in certain areas. This ASU is effective for the Company for fiscal years beginning after December 15, 2023, and interim periods within those fiscal years, with early adoption permitted for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of this principle on the Company’s consolidated financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , which is intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. This ASU is effective for public business entities for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of ASU 2019-12 on the Company’s consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses . This new guidance will require financial instruments to be measured at amortized cost, and trade accounts receivable to be presented at the net amount expected to be collected. The new model requires an entity to estimate credit losses based on historical information, current information and reasonable and supportable forecasts, including estimates of prepayments. In November 2019, the FASB issued ASU 2019-10, according to which, the new standard is effective for public business entities that meet the definition of an SEC filer, excluding entities eligible to be smaller reporting companies (“SRC”) as defined by the SEC, for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. For all other entities , the new standard is effective for fiscal years beginning after December 15, 2022, and interim periods within that fiscal year. Early adoption is permitted. The Company is a SRC for fiscal year 2019 and 2020. The Company is currently evaluating the impact of the new standard on the Company’s consolidated financial statements.
Assets and Liabilities Measured at Fair Value	Assets and liabilities recorded at fair value in the consolidated financial statements are categorized based upon the level of judgment associated with the inputs used to measure their fair value. Hierarchical levels which are directly related to the amount of subjectivity associated with the inputs to the valuation of these assets or liabilities are as follows: Level 1 – Inputs are unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access as of the measurement date. Level 2 – Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; Level 3 – Unobservable inputs for the asset or liability only used when there is little, if any, market activity for the asset or liability at the measurement date. This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value. Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis – Financial assets and liabilities held by the Company measured at fair value on a recurring basis include money market funds, short-term marketable securities, convertible preferred stock warrant liability and derivative liability. Assets and Liabilities Measured and Recorded at Fair Value on a Nonrecurring Basis – The Company determines the fair value of long-lived assets held and used, such as intangible assets, by reference to independent appraisals, quoted market prices (e.g. an offer to purchase) and other factors. An impairment charge is recorded when the carrying value of the asset exceeds its fair value. As noted above, there have been no impairment charges recorded to date. Based on the borrowing rates currently available to the Company for debt with similar terms and consideration of default and credit risk, the carrying value of the term loan and convertible note payable to related party approximates their fair value and is classified as a Level 2 liability. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability.
Derivative Liability	The Company valued the 2020 Notes derivative liability using the “with and without” methodology. The “with and without” methodology involves valuing the convertible note on an as is basis and then valuing the 2020 Notes without each individual embedded derivative. The difference between the value of the 2020 Notes with the embedded derivatives and the value without each individual embedded derivative equals the fair value of that embedded derivative. In April 2020, the Company valued the embedded derivatives using a Monte Carlo Simulation (“MCS”). The first step of each simulation was to forecast the Company’s Series G-1 convertible preferred stock price through the expiration of the 2020 Notes. In order to estimate the future share price of the Series G-1 convertible preferred stock, the Company applied a “random walk” model based upon a Geometric Brownian Motion process with a constant drift.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following tables summarizes the types of assets and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): December 31, 2020 Level 1 Level 2 Level 3 Total Assets: Money market funds $ 10,533 $ — $ — $ 10,533 Cash equivalents 10,533 — — 10,533 Total financial assets $ 10,533 $ — $ — $ 10,533 December 31, 2019 Level 1 Level 2 Level 3 Total Assets: Money market funds $ 6,318 $ — $ — $ 6,318 Commercial paper — 1,000 — 1,000 Cash equivalents 6,318 1,000 — 7,318 Corporate bonds — 7,105 — 7,105 Commercial paper — 6,475 — 6,475 Short-term marketable securities — 13,580 — 13,580 Total financial assets $ 6,318 $ 14,580 $ — $ 20,898 Liabilities: Preferred stock warrant liability $ — $ — $ — $ — Derivative liability — — 1,165 1,165 Total financial liabilities $ — $ — $ 1,165 $ 1,165
Schedule of Unrealized Gains and Losses and Fair Value of Marketable Securities	The following table summarizes the cost, unrealized gains and losses and fair value of marketable securities (in thousands): December 31, 2019 Amortized Cost Unrealized Losses Unrealized Gains Fair Value Corporate bonds $ 7,103 $ — $ 2 $ 7,105 Commercial paper 7,471 — 4 7,475 Marketable securities $ 14,574 $ — $ 6 $ 14,580 Amounts recognized on the consolidated balance sheet Cash equivalents $ 1,000 Short-term marketable securities 13,580 Marketable securities $ 14,580
Schedule of Assumptions Used in Determining Fair Value	The fair value of the Series C-1 convertible preferred stock warrants was determined using the following assumptions: December 31, 2019 Risk-free interest rate 1.6 % Remaining contractual life (in years) 0.1 Dividend yield 0 % Volatility 57.5 % The fair value of the 2020 Notes derivative liability was determined using the following assumptions: April 17, 2020 Risk-free interest rate 0.2 % Current Series G-1 convertible preferred stock value per share $ 0.84 Series G-1 convertible preferred stock volatility 34.4 %
Schedule of Fair Value of Liabilities	The change in fair value of the convertible preferred stock warrant liability and derivative liabilities is summarized below (in thousands): Convertible Preferred Stock Warrant Liability Success Fee Derivative Liability 2020 Notes Derivative Liability Beginning fair value, January 1, 2018 $ — $ — $ — Change in fair value 12 642 — Ending fair value, December 31, 2018 $ 12 $ 642 $ — Beginning fair value, January 1, 2019 12 642 — Change in fair value (12) 523 — Ending fair value, December 31, 2019 $ — $ 1,165 $ — Beginning fair value, January 1, 2020 — 1,165 — Fair value at inception — — 3,900 Change in fair value — 710 (3,900) Payment of Success Fee — (1,875) — Ending fair value, December 31, 2020 $ — $ — $ —

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Cash and Cash Equivalents	The Company’s cash and cash equivalents consist of the following (in thousands): December 31, 2020 2019 Cash $ 221,028 $ 7,449 Cash equivalents: Money market funds 10,533 6,318 Commercial paper — 1,000 Total cash and cash equivalents $ 231,561 $ 14,767
Schedule of Inventory	Inventory consists of the following (in thousands): December 31, 2020 2019 Raw materials $ 3,342 $ 1,950 Work in process 227 180 Finished goods 7,172 3,482 Total inventory $ 10,741 $ 5,612
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following (in thousands): December 31, 2020 2019 Prepaid expenses $ 381 $ 436 Prepaid insurance 2,131 12 VAT receivable 339 387 Other current assets 377 766 Total prepaid expenses and other current assets $ 3,228 $ 1,601
Schedule of Property and Equipment, Net	Property and equipment, net consist of the following (in thousands): December 31, 2020 2019 Machinery and equipment $ 1,447 $ 1,269 Computer equipment and software 1,062 848 Furniture and fixtures 229 168 Leasehold improvements 57 57 Construction in progress 452 — Total 3,247 2,342 Less: accumulated depreciation (1,773) (1,440) Property and equipment, net $ 1,474 $ 902
Schedule Intangible Assets	Intangible assets consist of the following (in thousands): December 31, 2020 Gross Carrying Value Accumulated Amortization Net Carrying Value Developed technology $ 1,658 $ (1,299) $ 359 Trademarks 191 (150) 41 Total intangible assets $ 1,849 $ (1,449) $ 400 December 31, 2019 Gross Carrying Value Accumulated Amortization Net Carrying Value Developed technology $ 1,658 $ (1,188) $ 470 Trademarks 191 (137) 54 Total intangible assets $ 1,849 $ (1,325) $ 524
Schedule of Future Amortization Expense	Future amortization expense is as follows (in thousands): Year Ending December 31, 2021 $ 123 2022 123 2023 123 2024 31 Total amortization expense $ 400
Schedule of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): December 31, 2020 2019 Accrued employee bonuses $ 2,374 $ 3,064 Accrued vacation 1,810 1,098 Other accrued personnel related expenses 1,368 705 Accrued professional fees 1,313 1,342 Accrued interest — 1,708 Sales taxes, franchise tax and VAT 521 762 Liability for early exercise of stock options 629 304 Other 636 480 Total accrued liabilities $ 8,651 $ 9,463

Long Term Debt and Convertibl_2

Long Term Debt and Convertible Notes (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The term loan consisted of the following (in thousands): December 31, 2020 2019 Term loan $ — $ 15,000 Less: debt issuance costs — (27) Less: deferred financing costs — (8) Term loan $ — $ 14,965 December 31, 2020 Term loan $ 17,000 Less: debt issuance costs (196) Term loan $ 16,804
Schedule of Contractual Maturities of Financing Obligations	As of December 31, 2020, the aggregate future payments under the CIBC Loan and Credit Agreement (including interest payments) are as follows (in thousands): 2021 723 2022 17,146 2023 — 2024 — 2025 564 Total 18,433 Less: unamortized debt discount (196) Less: interest (869) Term loan, convertible notes, and credit agreement $ 17,368

Leases, Commitments and Conti_2

Leases, Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Schedule of Operating Lease Cost and Additional Information	Operating lease cost consists of the following (in thousands): Years Ended December 31, 2020 2019 Operating lease cost $ 2,078 $ 1,037 Short-term lease cost 12 13 Variable lease cost 337 234 Total lease cost $ 2,427 $ 1,284 The following table summarizes balance sheet and other information related to our operating leases as (in thousands, except weighted average data): December 31, 2020 2019 Right of use asset $ 8,976 $ 6,561 Weighted average remaining lease term (years) 4.13 5.54 Weighted average discount rate (percent) 6.1 7.0 The following table summarizes other supplemental information related to our operating leases (in thousands): Years Ended December 31, 2020 2019 Cash paid for amounts included in the measurement of lease liabilities included in cash flows used in operating activities $ 1,494 $ 893 Right-of-use assets obtained in exchange for lease liabilities $ 3,935 $ 7,316
Schedule of Maturity Analysis of Lease Liabilities	The following table summarizes a maturity analysis of our lease liabilities showing the aggregate lease payments as of December 31, 2020 (in thousands): 2021 $ 2,769 2022 2,069 2023 2,795 2024 2,589 2025 1,007 Total minimum lease payments 11,229 Less: Amount of lease payments representing interest 1,373 Present value of future minimum lease payments $ 9,856 Less: Current lease liabilities $ 2,238 Long-term lease liabilities $ 7,618

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Income Before the Provision for Income Taxes	Income before the provision for income taxes consists of the following (in thousands): Years Ended December 31, 2020 2019 2018 Domestic $ (28,029) $ (17,142) $ (12,527) Foreign (3,989) (3,198) (5,940) Total loss before provision for taxes $ (32,018) $ (20,340) $ (18,467)
Schedule of Components of Income Tax Expense	The components of income tax expense are as follows (in thousands): Years Ended December 31, 2020 2019 2018 Current: Federal $ — $ — $ — State 9 10 2 Foreign 185 358 207 Total current expense 194 368 209 Deferred: Federal 6 7 (222) State 6 27 4 Foreign 7 (39) 21 Total deferred expense 19 (5) (197) Total income tax expense $ 213 $ 363 $ 12
Schedule of Reconciliation Between Federal Statutory Rate and Effective Rate	The reconciliation between the federal statutory rate and the Company’s effective tax rate is summarized below: Years Ended December 31, 2020 2019 2018 Federal statutory rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 10.2 % 2.7 % 1.0 % Foreign earnings at different rates (3.9) % (4.8) % (8.0) % Tax credits 0.6 % 0.6 % 0.9 % Permanent differences (0.3) % (0.4) % (0.3) % Prior year true-up 0.3 % 0.0 % (2.9) % Change in valuation allowance (40.5) % (20.9) % 10.7 % Expiration of net operating loss carryforwards and credits 0.0 % 0.0 % (22.5) % Entity restructuring 11.9 % 0.0 % 0.0 % Effective tax rate (0.7) % (1.8) % (0.1) %
Schedule of Significant Components Deferred Tax Assets and Liabilities	Significant components of the Company’s deferred tax assets and liabilities for federal and state income taxes are as follows (in thousands): December 31, 2020 2019 2018 Deferred tax assets: Net operating loss carryforwards $ 30,400 $ 22,500 $ 19,519 Tax credit carryforwards 5,240 4,896 4,659 Other 6,675 1,926 850 Gross deferred tax assets 42,315 29,322 25,028 Less: valuation allowance (41,922) (28,953) (24,736) Deferred tax assets 393 369 292 Deferred tax liabilities: Depreciation (27) (23) (17) Goodwill (428) (389) (323) Net deferred tax liabilities $ (62) $ (43) $ (48)
Schedule of Unrecognized Tax Benefits	The following table summarizes the activity related to the Company’s gross unrecognized tax benefits (in thousands): Balance at December 31, 2017 $ 1,070 Additions for tax positions related to current year 57 Reductions for tax positions related to prior year (185) Balance at December 31, 2018 $ 942 Additions for tax positions related to current year 47 Additions for tax positions related to prior year — Balance at December 31, 2019 $ 989 Additions for tax positions related to current year 7,259 Additions for tax positions related to prior year — Balance at December 31, 2020 $ 8,248

Warrants for Convertible Pref_2

Warrants for Convertible Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2020
Warrants and Rights Note Disclosure [Abstract]
Schedule of Outstanding Convertible Preferred Stock Warrants	A summary of the outstanding convertible preferred stock warrants is as follows (in thousands, except per share and share amounts): December 31, 2019 Exercise Price Shares Fair Value of Liability Expiration Date Series C-1 convertible preferred stock warrants $ 10.57 215,291 $ — February 9, 2020

Convertible Preferred Stock (Ta

Convertible Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2020
Temporary Equity Disclosure [Abstract]
Schedule of Convertible Preferred Stock	As of December 31, 2019, convertible preferred stock consists of the following (in thousands, except per share and share amounts): Series Number of Shares Authorized Number of Shares Issued and Outstanding Carrying Value(1) Liquidation Preference per Share Liquidation Value Series A-1 8,486,224 848,595 $ 8,135 $ 9.59 $ 8,138 Series B-1 24,224,676 2,422,444 23,130 10.57 25,605 Series C-1 39,422,980 3,726,974 37,306 10.57 39,395 Series D-1 9,400,000 939,979 10,268 11.00 10,340 Series E-1 9,230,768 923,049 11,896 13.00 12,000 Series F-1 37,878,787 3,787,878 49,800 13.20 50,000 Series G-1 49,342,376 4,934,231 64,804 13.20 65,132 Total 177,985,811 17,583,150 $ 205,339 $ 210,610 _______________ (1) Carrying values above are net of issuance costs.

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit) (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Schedule of Shares Reserved for Future Issuance	The Company has reserved shares of common stock for future issuances as follows: December 31, 2020 2019 Series A-1 convertible preferred stock outstanding — 848,595 Series B-1 convertible preferred stock outstanding — 2,422,444 Series C-1 convertible preferred stock outstanding — 3,726,974 Series D-1 convertible preferred stock outstanding — 939,979 Series E-1 convertible preferred stock outstanding — 923,049 Series F-1 convertible preferred stock outstanding — 3,787,878 Series G-1 convertible preferred stock outstanding — 4,934,231 Warrants to purchase Series C-1 convertible preferred stock — 215,291 Common stock options issued and outstanding 2,923,403 3,279,324 Common stock available for future grants 3,233,794 77,603 Common stock available for ESPP 720,000 — Total 6,877,197 21,155,368
Schedule of Summary of Stock Option Activity	Activity under the Stock Plans is set forth below: Outstanding Options Shares Available for Grant Number of Shares Weighted Average Exercise Price Balance, January 1, 2018 125,199 2,419,948 $ 1.52 Additional shares reserved 502,179 — $ — Options granted (255,900) 255,900 $ 1.37 Options exercised — (18,153) $ 1.68 Options canceled (1) 11,201 (31,201) $ 1.53 Balance, December 31, 2018 382,679 2,626,494 $ 1.51 Additional shares reserved 738,572 — — Options granted (1,078,957) 1,078,957 1.93 Options exercised — (390,318) 1.35 Options canceled (1) 35,309 (35,809) 1.39 Balance, December 31, 2019 77,603 3,279,324 $ 1.66 Additional shares reserved 4,553,378 — — Options granted (1,466,071) 1,466,071 7.73 Options exercised — (1,745,040) 1.55 Options canceled (1) 68,884 (76,952) 3.55 Balance, December 31, 2020 3,233,794 2,923,403 $ 4.72 ______________ (1) Canceled stock options issued under the Company’s 2000 Stock Plan were canceled after the 2010 Stock Plan was approved and are not included in the shares available for grant as they were not returned to the stock option pool.
Schedule of Options Vested and Expected to Vest	December 31, 2020 Number of Shares Weighted Average Exercise Price Weighted Average Contractual Life (in Years) Options vested 1,219,241 $ 2.03 5.23 Options vested and expected to vest 2,923,403 $ 4.72 7.63
Schedule of Stock Options Valuation Assumptions	The estimated grant date fair values of employee stock options were calculated using the following assumptions: Years Ended December 31, 2020 2019 2018 Weighted average expected term (in years) 5.0 - 6.1 5.3 - 6.1 6.3 Volatility 40.0% - 44.7% 47.1% - 49.7% 46.0% Risk-free interest rate 0.2% - 1.7% 1.4% - 1.8% 2.4%-2.9% Dividend yield — — —
Schedule of Compensation Expense Valuation Assumptions	Compensation expense is calculated using the fair value of the employees' purchase rights under the Black-Scholes model. Year Ended December 31, 2020 Weighted average expected term (in years) 0.6 Volatility 67.7% - 68.2% Risk-free interest rate 0.1% Dividend yield —
Schedule of Total Stock-Based Compensation	Stock-based compensation expense is reflected in the statements of operations and comprehensive loss as follows (in thousands): Years Ended December 31, 2020 2019 2018 Cost of goods sold $ 39 $ 30 $ 18 Research and development 398 64 62 Selling, general and administrative 2,760 270 286 Total $ 3,197 $ 364 $ 366 The above stock-based compensation expense related to the following equity-based awards: Years Ended December 31, 2020 2019 2018 Stock options $ 2,055 $ 364 $ 366 ESPP 1,142 — — Total $ 3,197 $ 364 $ 366

Net Loss per Share Attributab_2

Net Loss per Share Attributable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss per Share	The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders which excludes shares which are legally outstanding, but subject to repurchase by the Company (in thousands, except share and per share amounts): Years Ended December 31, 2020 2019 2018 Numerator Net loss attributable to common stockholders $ (32,231) $ (20,703) $ (18,479) Denominator Weighted-average common stock outstanding 10,341,809 1,796,233 1,706,654 Less: weighted-average common shares subject to repurchase (156,968) (20,123) (31,875) Weighted-average common shares used to compute basic and diluted net loss per share 10,184,841 1,776,110 1,674,779 Net loss per share attributable to common stockholders, basic and diluted $ (3.16) $ (11.66) $ (11.03)
Schedule of Potentially Dilutive Securities Outstanding	The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted average shares outstanding because such securities have an antidilutive impact due to the Company’s net loss, in common stock equivalent shares: Years Ended December 31, 2020 2019 2018 Convertible preferred stock — 17,583,150 12,648,919 Convertible preferred stock warrants — 215,291 215,291 Options to purchase common stock 2,923,403 3,279,324 2,626,494 Unvested early exercised common stock options 355,677 199,810 26,852 Shares committed under ESPP 47,174 — — Conversion of convertible notes* — — — ______________

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Schedule of Revenue by Geographic Area	Revenue by geographic area is based on the billing address of the customer. The following table sets forth our revenue by geographic area (in thousands): Year Ended December 31, 2020 2019 2018 United States $ 16,189 $ 10,704 $ 563 Europe, Middle-East and Africa 13,808 18,364 16,175 Asia Pacific 2,687 3,227 3,115 Other International 49 300 151 Total $ 32,733 $ 32,595 $ 20,004
Schedule of Long-lived Assets by Geographic Area	Long-lived assets by geographic area are based on physical location of those assets. The following table sets forth our long-lived assets by geographic area (in thousands): December 31, 2020 2019 United States $ 1,437 $ 852 Europe, Middle-East and Africa 29 40 Asia Pacific 8 10 Total $ 1,474 $ 902

Selected Quarterly Financial _2

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Selected Quarterly Financial Information	The following table provides the selected quarterly financial information for the years 2020 and 2019 (in thousands, except per share data): Three months ended March 31, 2020 June 30, 2020 September 30, 2020 December 31, 2020 Revenue $ 8,618 $ 3,673 $ 10,612 $ 9,830 Gross profit $ 5,650 $ 1,012 $ 7,462 $ 7,078 Net loss $ (7,163) $ (11,911) $ (3,860) $ (9,297) Net loss per share attributable to common $ (3.76) $ (6.15) $ (1.37) $ (0.27) Three months ended March 31, 2019 June 30, 2019 September 30, 2019 December 31, 2019 Revenue $ 5,778 $ 7,366 $ 9,104 $ 10,347 Gross profit $ 3,717 $ 4,953 $ 6,407 $ 7,337 Net loss $ (6,128) $ (5,571) $ (4,335) $ (4,669) Net loss per share attributable to common $ (3.61) $ (3.24) $ (2.41) $ (2.48)

Formation and Business of the_2

Formation and Business of the Company (Details) - USD ($) $ / shares in Units, $ in Thousands	Oct. 05, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Subsidiary, Sale of Stock [Line Items]
Accrued interest		$ 869
Common stock, shares authorized (in shares)	200,000,000	200,000,000	240,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized (in shares)	10,000,000	0	177,985,811
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Accumulated deficit		$ 242,734	$ 210,503
Cash used in operating activities		30,633	20,765	$ 18,394
Cash and cash equivalents		$ 231,561	$ 14,767	$ 4,124
2020 Notes Agreement
Subsidiary, Sale of Stock [Line Items]
Convertible debt	$ 33,000
Accrued interest	800
2020 Notes Agreement | Convertible Debt
Subsidiary, Sale of Stock [Line Items]
Accrued interest	$ 800
2020 Notes Agreement | Convertible Debt | Common Stock
Subsidiary, Sale of Stock [Line Items]
Shares issued upon conversion of debt (in shares)	2,561,484
Common Stock
Subsidiary, Sale of Stock [Line Items]
Conversion of convertible securities (in shares)	17,797,026	17,797,026
Common Stock | Convertible Debt
Subsidiary, Sale of Stock [Line Items]
Conversion of convertible securities (in shares)		2,561,484
IPO
Subsidiary, Sale of Stock [Line Items]
Shares issued in transaction (in shares)	11,500,000
Share price (in dollars per share)	$ 19
Proceeds from initial public offering	$ 218,500
Proceeds from initial public offering, net of issuance costs	$ 201,400
Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Shares issued in transaction (in shares)	1,500,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details)	Sep. 22, 2020	May 31, 2020USD ($)	Dec. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stock split ratio	100,000
Short-term marketable securities			$ 0	$ 13,580,000
Cash on deposit with foreign banks			5,600,000	5,200,000
Deferred offering costs			0	1,563,000
Write-off of deferred offering costs			3,000,000
Payments for issuance costs upon IPO		$ 1,800,000
Allowance for doubtful accounts (less than for 2019)			$ 0	100,000
Number of operating segments | segment			1
Number of reporting units | segment			1
Intangible assets useful life			15 years
Deferred revenue			$ 100,000	200,000	$ 100,000
Revenue recognized			200,000	100,000
Advertising costs			1,500,000	600,000	100,000
Other comprehensive loss, foreign currency translation adjustments			318,000	34,000	126,000
Foreign currency transaction gains and (losses)			$ 100,000	(100,000)	(300,000)
Minimum
Accumulated Other Comprehensive Income (Loss) [Line Items]
Property and equipment, useful life			3 years
Payment term			30 days
Maximum
Accumulated Other Comprehensive Income (Loss) [Line Items]
Property and equipment, useful life			5 years
Payment term			60 days
Other comprehensive loss, foreign currency translation adjustments			$ 300,000	$ 100,000	$ 100,000

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Assets and Liabilities (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Assets:
Short-term marketable securities	$ 0	$ 13,580,000
Recurring Basis
Assets:
Cash equivalents	10,533,000	7,318,000
Short-term marketable securities		13,580,000
Total financial assets	10,533,000	20,898,000
Liabilities:
Preferred stock warrant liability		0
Derivative liability		1,165,000
Total financial liabilities		1,165,000
Recurring Basis | Corporate bonds
Assets:
Short-term marketable securities		7,105,000
Recurring Basis | Commercial paper
Assets:
Short-term marketable securities		6,475,000
Level 1 | Recurring Basis
Assets:
Cash equivalents	10,533,000	6,318,000
Short-term marketable securities		0
Total financial assets	10,533,000	6,318,000
Liabilities:
Preferred stock warrant liability		0
Derivative liability		0
Total financial liabilities		0
Level 1 | Recurring Basis | Corporate bonds
Assets:
Short-term marketable securities		0
Level 1 | Recurring Basis | Commercial paper
Assets:
Short-term marketable securities		0
Level 2 | Recurring Basis
Assets:
Cash equivalents	0	1,000,000
Short-term marketable securities		13,580,000
Total financial assets	0	14,580,000
Liabilities:
Preferred stock warrant liability		0
Derivative liability		0
Total financial liabilities		0
Level 2 | Recurring Basis | Corporate bonds
Assets:
Short-term marketable securities		7,105,000
Level 2 | Recurring Basis | Commercial paper
Assets:
Short-term marketable securities		6,475,000
Level 3 | Recurring Basis
Assets:
Cash equivalents	0	0
Short-term marketable securities		0
Total financial assets	0	0
Liabilities:
Preferred stock warrant liability		0
Derivative liability		1,165,000
Total financial liabilities		1,165,000
Level 3 | Recurring Basis | Corporate bonds
Assets:
Short-term marketable securities		0
Level 3 | Recurring Basis | Commercial paper
Assets:
Short-term marketable securities		0
Money market funds | Recurring Basis
Assets:
Cash equivalents	10,533,000	6,318,000
Money market funds | Level 1 | Recurring Basis
Assets:
Cash equivalents	10,533,000	6,318,000
Money market funds | Level 2 | Recurring Basis
Assets:
Cash equivalents	0	0
Money market funds | Level 3 | Recurring Basis
Assets:
Cash equivalents	$ 0	0
Commercial paper | Recurring Basis
Assets:
Cash equivalents		1,000,000
Commercial paper | Level 1 | Recurring Basis
Assets:
Cash equivalents		0
Commercial paper | Level 2 | Recurring Basis
Assets:
Cash equivalents		1,000,000
Commercial paper | Level 3 | Recurring Basis
Assets:
Cash equivalents		$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details)	Oct. 05, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Derivative [Line Items]
Marketable securities		$ 0	$ 13,580,000
Accrued interest on marketable securities			100,000
Payments of debt fees		$ 1,875,000	0	$ 0
Oxford Finance Loan | Medium-term Notes
Derivative [Line Items]
Payments of debt fees	$ 1,900,000
Success Fee Derivative
Derivative [Line Items]
Success Fee amount	$ 1,900,000		$ 1,200,000
Measurement Input, Probability Of Liquidity Event | Success Fee Derivative
Derivative [Line Items]
Derivative liability, measurement input			0.65

Fair Value Measurements - Cost,

Fair Value Measurements - Cost, Unrealized Gains and Losses and Fair Value (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost		$ 14,574,000
Unrealized Losses		0
Unrealized Gains		6,000
Fair Value		14,580,000
Short-term marketable securities	$ 0	13,580,000
Corporate bonds
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost		7,103,000
Unrealized Losses		0
Unrealized Gains		2,000
Fair Value		7,105,000
Commercial paper
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost		7,471,000
Unrealized Losses		0
Unrealized Gains		4,000
Fair Value		7,475,000
Cash equivalents		$ 1,000,000

Fair Value Measurements - Valua

Fair Value Measurements - Valuation Assumptions (Details) - Valuation Technique, Option Pricing Model	Apr. 17, 2020$ / shares	Dec. 31, 2019
Risk-free interest rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible preferred stock warrants, measurement input		0.016
Remaining contractual life (in years)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible preferred stock warrants, measurement input		0.1
Dividend yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible preferred stock warrants, measurement input		0
Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible preferred stock warrants, measurement input		0.575
2020 Notes Derivative Liability | Risk-free interest rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.002
2020 Notes Derivative Liability | Current Series G-1 convertible preferred stock value per share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.84
2020 Notes Derivative Liability | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.344

Fair Value Measurements - Fai_2

Fair Value Measurements - Fair Value of Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Convertible Preferred Stock Warrant Liability
Convertible Preferred Stock Warrant Liability
Beginning fair value	$ 0	$ 12	$ 0
Change in fair value	0	(12)	12
Ending fair value	0	0	12
Derivative Liability
Payment of Success Fee	0
Success Fee Derivative Liability
Derivative Liability
Beginning fair value	1,165	642	0
Change in fair value	710	523	642
Payment of Success Fee	(1,875)
Ending fair value	0	1,165	$ 642
2020 Notes Derivative Liability
Derivative Liability
Beginning fair value	0
Fair value at inception	3,900
Change in fair value	(3,900)
Payment of Success Fee	0
Ending fair value	$ 0	$ 0

Balance Sheet Components - Cash

Balance Sheet Components - Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash	$ 221,028	$ 7,449
Cash equivalents:
Money market funds	10,533	6,318
Commercial paper	0	1,000
Total cash and cash equivalents	$ 231,561	$ 14,767	$ 4,124

Balance Sheet Components - Inve

Balance Sheet Components - Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials	$ 3,342	$ 1,950
Work in process	227	180
Finished goods	7,172	3,482
Total inventory	$ 10,741	$ 5,612

Balance Sheet Components - Prep

Balance Sheet Components - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Prepaid expenses	$ 381	$ 436
Prepaid insurance	2,131	12
VAT receivable	339	387
Other current assets	377	766
Total prepaid expenses and other current assets	$ 3,228	$ 1,601

Balance Sheet Components - Prop

Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 3,247	$ 2,342
Less: accumulated depreciation	(1,773)	(1,440)
Property and equipment, net	1,474	902
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	1,447	1,269
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	1,062	848
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	229	168
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	57	57
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 452	$ 0

Balance Sheet Components - Narr

Balance Sheet Components - Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Depreciation expense			$ 300,000	$ 200,000	$ 100,000
Goodwill	$ 2,333,000	$ 2,333,000	2,333,000	2,333,000
Goodwill, accumulated impairment loss	0		0
Goodwill acquired			0	0
Goodwill disposed of			0
Goodwill, impairment loss	$ 0	$ 0
Amortization expense related to intangibles			$ 100,000	$ 100,000	$ 100,000

Balance Sheet Components - Inta

Balance Sheet Components - Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 1,849	$ 1,849
Accumulated Amortization	(1,449)	(1,325)
Net Carrying Value	400	524
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,658	1,658
Accumulated Amortization	(1,299)	(1,188)
Net Carrying Value	359	470
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	191	191
Accumulated Amortization	(150)	(137)
Net Carrying Value	$ 41	$ 54

Balance Sheet Components - Futu

Balance Sheet Components - Future Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2021	$ 123
2022	123
2023	123
2024	31
Net Carrying Value	$ 400	$ 524

Balance Sheet Components - Accr

Balance Sheet Components - Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued employee bonuses	$ 2,374	$ 3,064
Accrued vacation	1,368	705
Other accrued personnel related expenses	1,810	1,098
Accrued professional fees	1,313	1,342
Accrued interest	0	1,708
Sales taxes, franchise tax and VAT	521	762
Liability for early exercise of stock options	629	304
Other	636	480
Total accrued liabilities	$ 8,651	$ 9,463

Long Term Debt And Convertibl_3

Long Term Debt And Convertible Notes - Oxford Finance Loan Narrative (Details) - USD ($)	Oct. 05, 2020	Feb. 20, 2020	Aug. 28, 2014	May 31, 2018	Aug. 31, 2014	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2014	May 31, 2017
Debt Instrument [Line Items]
Payments of debt fees						$ 1,875,000	$ 0	$ 0
Fees and legal expenses						196,000
Payment of fees to lender and third parties						162,000	0	0
Interest expense on deferred financing and debt issuance costs, less than						968,000	28,000	$ 36,000
Success Fee Derivative
Debt Instrument [Line Items]
Derivative liability	$ 1,900,000						$ 1,200,000
Medium-term Notes | Oxford Finance Loan
Debt Instrument [Line Items]
Debt instrument, face amount including accordion feature					$ 20,000,000
Proceeds from issuance of debt									$ 15,000,000
Accordion feature on face amount of debt					$ 5,000,000
Stated interest rate					8.96%
Debt term					5 years
Interest payments term					36 months
Principal and interest payments term					24 months
Final payment, percentage of loan amount due					8.50%
Incremental fee amount due at maturity										$ 100,000
Fee amount		$ 900,000		$ 800,000						$ 400,000
Effective interest rate		11.11%					11.11%	11.17%
Contingent fee amount, maximum					$ 2,500,000
Contingent fee amount						1,900,000	$ 1,900,000
Payments of debt fees	$ 1,900,000
Repayments on term loan obligations		$ 17,300,000
Extinguishment of debt		15,000,000
Final payment on loan		1,300,000
Accrued interest		100,000
Loss on extinguishment of debt		$ 400,000
Fees and legal expenses				$ 100,000		0	8,000
Payment of fees to lender and third parties						200,000
Interest expense on deferred financing and debt issuance costs, less than						100,000	100,000	$ 100,000
Interest expense						$ 400,000	$ 1,700,000	$ 1,700,000
Medium-term Notes | Oxford Finance Loan | 18 Months After August 28, 2014
Debt Instrument [Line Items]
Contingent fee amount, percentage of loan					6.25%
Contingent fee amount, term			18 months
Medium-term Notes | Oxford Finance Loan | Between 18 Months and 3 Years After August 28, 2014
Debt Instrument [Line Items]
Contingent fee amount, percentage of loan					8.75%
Medium-term Notes | Oxford Finance Loan | After Third Anniversary of August 28, 2014
Debt Instrument [Line Items]
Contingent fee amount, percentage of loan					12.50%
Medium-term Notes | Oxford Finance Loan | Debt Instrument, Covenant, Scenario One
Debt Instrument [Line Items]
Stated interest rate					8.71%
Medium-term Notes | Oxford Finance Loan | Debt Instrument, Covenant, Scenario Two
Debt Instrument [Line Items]
Component of annual rate calculation, percentage in addition to LIBOR rate				6.86%
Medium-term Notes | Oxford Finance Loan | Minimum | Between 18 Months and 3 Years After August 28, 2014
Debt Instrument [Line Items]
Contingent fee amount, term			18 months
Medium-term Notes | Oxford Finance Loan | Maximum | Between 18 Months and 3 Years After August 28, 2014
Debt Instrument [Line Items]
Contingent fee amount, term			3 years
Medium-term Notes | Oxford Finance Loan | London Interbank Offered Rate (LIBOR) | Debt Instrument, Covenant, Scenario Two
Debt Instrument [Line Items]
Basis spread on variable rate				1.85%

Long Term Debt and Convertibl_4

Long Term Debt and Convertible Notes - Oxford Finance Loan Components of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	May 31, 2018
Debt Instrument [Line Items]
Term loan	$ 18,433
Less: deferred financing costs	(196)
Term loan, convertible notes, and credit agreement	17,368
Medium-term Notes | Oxford Finance Loan
Debt Instrument [Line Items]
Term loan	0	$ 15,000
Less: debt issuance costs	0	(27)
Less: deferred financing costs	0	(8)	$ (100)
Term loan, convertible notes, and credit agreement	$ 0	$ 14,965

Long Term Debt and Convertibl_5

Long Term Debt and Convertible Notes - CIBC Loan Narrative (Details) - USD ($)	Feb. 20, 2020	Apr. 30, 2020	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Payment of fees to lender and third parties				$ 162,000	$ 0	$ 0
Amortization of debt discount and debt issuance costs				$ 968,000	$ 28,000	$ 36,000
CIBC Agreement | Medium-term Notes
Debt Instrument [Line Items]
Debt instrument, face amount including accordion feature	$ 32,000,000
Debt term	5 years
Interest payments term	24 months
Principal and interest payments term	36 months
Interest period extension term	36 months
Interest-only period, training period of revenue requirement	3 months
Revenue threshold for interest period extension term option	$ 20,000,000
Fee amount		$ 200,000
Effective interest rate			5.16%	5.16%
Minimum percentage of revenue requirement, trailing period of revenue	3 months
Minimum percentage of revenue requirement	80.00%
Unrestricted cash requirement period	4 months
Payment of fees to lender and third parties	$ 300,000
Amortization of debt discount and debt issuance costs			$ 100,000
Interest expense			$ 700,000
CIBC Agreement | Medium-term Notes | Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
CIBC Agreement, Tranche A | Medium-term Notes
Debt Instrument [Line Items]
Proceeds from issuance of debt	$ 17,000,000
CIBC Agreement, Tranche B | Medium-term Notes
Debt Instrument [Line Items]
Accordion feature on face amount of debt	8,000,000
Trailing period of revenue		6 months
Revenue threshold for additional borrowing		$ 15,000,000
CIBC Agreement, Tranche C | Medium-term Notes
Debt Instrument [Line Items]
Accordion feature on face amount of debt	$ 7,000,000
Trailing period of revenue	6 months
Revenue threshold for additional borrowing	$ 20,000,000
CIBC Agreement, Tranche C | Medium-term Notes | Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate	1.50%
CIBC Agreement, Tranche B Or Tranche C | Medium-term Notes
Debt Instrument [Line Items]
Structuring fee percentage		1.00%

Long Term Debt and Convertibl_6

Long Term Debt and Convertible Notes - CIBC Loan Components Of Debt (Details) $ in Thousands	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Term loan	$ 18,433
Less: deferred financing costs	(196)
Outstanding loan amount	17,368
CIBC Agreement | Medium-term Notes
Debt Instrument [Line Items]
Term loan	17,000
Less: deferred financing costs	(196)
Outstanding loan amount	$ 16,804

Long Term Debt and Convertibl_7

Long Term Debt and Convertible Notes - Credit Agreement and Paycheck Protection Program Narrative (Details)	Apr. 16, 2020USD ($)	May 31, 2020USD ($)	Apr. 30, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Apr. 30, 2020CHF (SFr)
Debt Instrument [Line Items]
Proceeds from PPP				$ 2,666,000	$ 0	$ 0
Paycheck Protection Program, CARES Act
Debt Instrument [Line Items]
Proceeds from PPP	$ 2,700,000
Line of Credit | COVID-19 Credit Agreement | Pulmonx International Sarl
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 500,000				SFr 500,000
Proceeds from Credit Agreement		$ 500,000
Debt term			60 months
Repayments on credit agreement				$ 0

Long Term Debt and Convertibl_8

Long Term Debt and Convertible Notes - Convertible Notes Narrative (Details) - USD ($)

Oct. 05, 2020

Jun. 01, 2017

Apr. 30, 2020

Apr. 30, 2019

Jan. 31, 2019

May 31, 2017

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Oct. 04, 2020

Jul. 01, 2018

Debt Instrument [Line Items]

Proceeds from convertible debt

$ 32,950,000

$ 6,000,000

$ 12,000,000

Conversion of convertible note into Series G-1 convertible preferred stock

0

25,133,000

0

Debt issuance costs

162,000

0

0

Embedded derivative liability

$ 3,900,000

Accrued interest

869,000

Amortization of debt discount and debt issuance costs

968,000

$ 28,000

36,000

2020 Notes Derivative Liability

Debt Instrument [Line Items]

Increase (decrease) in fair value of derivative

3,900,000

2020 Notes Agreement

Debt Instrument [Line Items]

Convertible debt

$ 33,000,000

Accrued interest

800,000

Convertible Debt | Second Lien Loan And Security Agreement

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 30,000,000

Stated interest rate

8.96%

Prepayment conversion, amount divided by fully-diluted shares upon conversion

230,000,000

Proceeds from convertible debt

$ 6,000,000

12,000,000

$ 6,000,000

Conversion of convertible note into Series G-1 convertible preferred stock

$ 25,100,000

Gain on extinguishment of debt, less than

$ 100,000

Debt issuance costs

$ 100,000

Interest expense

$ 800,000

Effective interest rate

7.47%

Convertible Debt | Second Lien Loan And Security Agreement | Right Of First Negotiation Period

Debt Instrument [Line Items]

Exercise period

5 days

10 days

Convertible Debt | Second Lien Loan And Security Agreement | Exclusive Negotiation Period

Debt Instrument [Line Items]

Exercise period

45 days

75 days

Convertible Debt | Second Lien Loan And Security Agreement | Right Of First Negotiation For Subsequent Notices

Debt Instrument [Line Items]

Exercise period

10 days

Convertible Debt | Second Lien Loan And Security Agreement | Exclusive Negotiation Period For Subsequent Notices

Debt Instrument [Line Items]

Exercise period

75 days

Convertible Debt | Second Lien Loan And Security Agreement | Series G-1

Debt Instrument [Line Items]

Shares issued upon conversion of debt (in shares)

1,903,935

Conversion price per share (in dollars per share)

$ 13.20

Convertible Debt | 2020 Notes Agreement

Debt Instrument [Line Items]

Maximum borrowing capacity

66,000,000

Debt issuance costs

100,000

Interest expense

1,600,000

Effective interest rate

12.33%

Remaining borrowing capacity

33,000,000

Threshold stock proceeds for conversion

$ 30,000,000

Accrued interest

$ 800,000

Contractual interest expense

800,000

Amortization of debt discount and debt issuance costs

$ 800,000

Convertible Debt | 2020 Notes Agreement | Prime Rate

Debt Instrument [Line Items]

Basis spread on variable rate

2.00%

Convertible Debt | 2020 Notes Agreement | Common Stock

Debt Instrument [Line Items]

Shares issued upon conversion of debt (in shares)

2,561,484

Conversion price per share (in dollars per share)

$ 13.20

Convertible Debt | 2020 Notes Agreement | Debt Instrument, Convertible, Conversion Feature, Scenario Two

Debt Instrument [Line Items]

Conversion price per share (in dollars per share)

$ 13.20

Convertible Debt | 2020 Notes Agreement | Debt Instrument, Convertible, Conversion Feature, Scenario Two | Series G-1

Debt Instrument [Line Items]

Conversion price per share (in dollars per share)

$ 13.20

Convertible Debt | 2020 Notes Agreement | Debt Instrument, Convertible, Conversion Feature, Non-Qualified Financing Scenario

Debt Instrument [Line Items]

Threshold stock proceeds from non-significant holders for conversion

$ 10,000,000

Threshold of debt for Significant Holder

$ 20,000,000

Convertible Debt | 2020 Notes Agreement | Debt Instrument, Conversion Feature, Non-Qualified Financing, Scenario One

Debt Instrument [Line Items]

Percentage of stock price

75.00%

Convertible Debt | 2020 Notes Agreement | Debt Instrument, Convertible, Conversion Feature, Non-Qualified Financing, Scenario Two

Debt Instrument [Line Items]

Percentage of stock price

75.00%

Convertible Debt | 2020 Notes Agreement | Debt Instrument, Convertible, Conversion Feature, Non-Qualified Financing, Scenario Two | Series G-1

Debt Instrument [Line Items]

Conversion price per share (in dollars per share)

$ 13.20

Convertible Debt | 2020 Notes Agreement | Debt Instrument, Convertible, Conversion Feature, Qualified IPO Scenario

Debt Instrument [Line Items]

Stock proceeds threshold for conversion

$ 30,000,000

Convertible Debt | 2020 Notes Agreement | Debt Instrument, Convertible, Conversion Feature, Qualified IPO, Scenario Two

Debt Instrument [Line Items]

Conversion price per share (in dollars per share)

$ 13.20

Convertible Debt | 2020 Notes Agreement | Debt Instrument, Convertible, Conversion Feature, Non-Qualified IPO, Scenario One

Debt Instrument [Line Items]

Percentage of stock price

75.00%

Convertible Debt | 2020 Notes Agreement | Debt Instrument, Convertible, Conversion Feature, Non-Qualified IPO, Scenario Two

Debt Instrument [Line Items]

Percentage of stock price

75.00%

Convertible Debt | 2020 Notes Agreement | Debt Instrument, Convertible, Conversion Feature, Non-Qualified IPO, Scenario Two | Series G-1

Debt Instrument [Line Items]

Conversion price per share (in dollars per share)

$ 13.20

Convertible Debt | 2020 Notes Agreement | Debt Instrument, Convertible, Conversion Feature, Default Scenario

Debt Instrument [Line Items]

Percentage of stock price

75.00%

Convertible Debt | 2020 Notes Agreement | Debt Covenant, Eighteen Months After Initial Closing | Debt Instrument, Convertible, Conversion Feature, Scenario One

Debt Instrument [Line Items]

Percentage of stock price

85.00%

Convertible Debt | 2020 Notes Agreement | Debt Covenant, Eighteen Months After Initial Closing | Debt Instrument, Convertible, Conversion Feature, Qualified IPO, Scenario One

Debt Instrument [Line Items]

Percentage of stock price

85.00%

Convertible Debt | 2020 Notes Agreement | Debt Covenant, Eighteen Months After Initial Closing, Thereafter | Debt Instrument, Convertible, Conversion Feature, Scenario One

Debt Instrument [Line Items]

Percentage of stock price

80.00%

Convertible Debt | 2020 Notes Agreement | Debt Covenant, Eighteen Months After Initial Closing, Thereafter | Debt Instrument, Convertible, Conversion Feature, Qualified IPO, Scenario Two

Debt Instrument [Line Items]

Percentage of stock price

80.00%

Convertible Debt | 2020 Notes Agreement, Tranche One

Debt Instrument [Line Items]

Proceeds from convertible debt

$ 33,000,000

Convertible Debt | 2020 Notes Agreement, Tranche Two | Maximum

Debt Instrument [Line Items]

Remaining borrowing capacity

33,000,000

Convertible Debt | 2020 Notes Agreement Over Allotment Option

Debt Instrument [Line Items]

Maximum draw amount

$ 5,000,000

Long Term Debt and Convertibl_9

Long Term Debt and Convertible Notes - Convertible Notes Components of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Oct. 05, 2020
Debt Instrument [Line Items]
Term loan	$ 18,433
Outstanding loan amount	$ 17,368
2020 Notes Agreement
Debt Instrument [Line Items]
Convertible debt		$ 33,000

Long Term Debt and Convertib_10

Long Term Debt and Convertible Notes - Contractual Maturities of Financing Obligations (Details) $ in Thousands	Dec. 31, 2020USD ($)
Long-term Debt, Fiscal Year Maturity [Abstract]
2021	$ 723
2022	17,146
2023	0
2024	0
2025	564
Total	18,433
Less: unamortized debt discount	(196)
Less: interest	(869)
Outstanding loan amount	$ 17,368

Leases, Commitments and Conti_3

Leases, Commitments and Contingencies - Narrative (Details) $ in Millions	1 Months Ended			12 Months Ended
	Sep. 30, 2020USD ($)	Aug. 31, 2020USD ($)	Apr. 30, 2020USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2013	Dec. 31, 2020lease
Lessee, Lease, Description [Line Items]
Lease renewal term		5 years
Monthly base rent		$ 0.1
Annual increase rate		3.50%
Tenant improvement allowance, receivable upon lease renewal		$ 0.2
Option to terminate, notice period					12 months
Sublease term	4 years		3 years
Early termination notice period			180 days
Sublease, period for option to terminate			18 months
Sublease monthly rent	$ 0.1		$ 0.1
Monthly base rent, annual increase rate	3.50%		3.50%
Tenant improvement allowance, receivable upon sublease renewal	$ 0.6
Sublease renewal term	12 months
Number of vehicle leases | lease						2
Rent expense				$ 1
Office Facilities
Lessee, Lease, Description [Line Items]
Lease term					5 years
Minimum | Vehicles
Lessee, Lease, Description [Line Items]
Lease term						2 years
Maximum | Vehicles
Lessee, Lease, Description [Line Items]
Lease term						4 years

Leases, Commitments and Conti_4

Leases, Commitments and Contingencies - Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease cost	$ 2,078	$ 1,037
Short-term lease cost	12	13
Variable lease cost	337	234
Total lease cost	$ 2,427	$ 1,284

Leases, Commitments and Conti_5

Leases, Commitments and Contingencies - Maturity Analysis of Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 2,769
2022	2,069
2023	2,795
2024	2,589
2025	1,007
Total minimum lease payments	11,229
Less: Amount of lease payments representing interest	1,373
Present value of future minimum lease payments	9,856
Less: Current lease liabilities	2,238	$ 446
Long-term lease liabilities	$ 7,618	$ 6,403

Leases, Commitments and Conti_6

Leases, Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Right of use asset	$ 8,976	$ 6,561
Weighted average remaining lease term (years)	4 years 1 month 17 days	5 years 6 months 14 days
Weighted average discount rate (percent)	6.10%	7.00%

Leases, Commitments and Conti_7

Leases, Commitments and Contingencies - Other Supplemental Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities included in cash flows used in operating activities	$ 1,494	$ 893
Right-of-use assets obtained in exchange for lease liabilities	$ 3,935	$ 7,316

Income Taxes - Income Before Co

Income Taxes - Income Before Continuing Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Domestic	$ (28,029)	$ (17,142)	$ (12,527)
Foreign	(3,989)	(3,198)	(5,940)
Net loss before tax	$ (32,018)	$ (20,340)	$ (18,467)

Income Taxes - Components of In

Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ 0	$ 0	$ 0
State	9	10	2
Foreign	185	358	207
Total current expense	194	368	209
Deferred:
Federal	6	7	(222)
State	6	27	4
Foreign	7	(39)	21
Total deferred expense	19	(5)	(197)
Income tax expense	$ 213	$ 363	$ 12

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Statutory to Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal statutory rate	21.00%	21.00%	21.00%
State taxes, net of federal benefit	10.20%	2.70%	1.00%
Foreign earnings at different rates	(3.90%)	(4.80%)	(8.00%)
Tax credits	0.60%	0.60%	0.90%
Permanent differences	(0.30%)	(0.40%)	(0.30%)
Prior year true-up	0.30%	(0.00%)	(2.90%)
Change in valuation allowance	(40.50%)	(20.90%)	10.70%
Expiration of net operating loss carryforwards and credits	0.00%	0.00%	(22.50%)
Entity restructuring	11.90%	0.00%	0.00%
Effective tax rate	(0.70%)	(1.80%)	(0.10%)

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$ 30,400	$ 22,500	$ 19,519
Tax credit carryforwards	5,240	4,896	4,659
Other	6,675	1,926	850
Gross deferred tax assets	42,315	29,322	25,028
Less: valuation allowance	(41,922)	(28,953)	(24,736)
Deferred tax assets	393	369	292
Deferred tax liabilities:
Depreciation	(27)	(23)	(17)
Goodwill	(428)	(389)	(323)
Net deferred tax liabilities	$ (62)	$ (43)	$ (48)

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Tax Credit Carryforward [Line Items]
Valuation allowance	$ 41,922	$ 28,953	$ 24,736
Increase (decrease) in deferred tax asset valuation allowance	13,000	4,200	(2,000)
Write off of net operating losses			3,100
Write off of tax credits			1,200
Unrecognized tax benefits	8,248	$ 989	$ 942	$ 1,070
Federal
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	122,500
Federal | Tax Year 2018
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	50,500
State
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	90,300
Research and Development | Federal
Tax Credit Carryforward [Line Items]
Tax credit carryforward	2,800
Research and Development | State
Tax Credit Carryforward [Line Items]
Tax credit carryforward	$ 4,200

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 989	$ 942	$ 1,070
Additions for tax positions related to current year	7,259	47	57
Reductions for tax positions related to prior year			(185)
Additions for tax positions related to prior year	0	0
Balance at end of period	$ 8,248	$ 989	$ 942

Warrants for Convertible Pref_3

Warrants for Convertible Preferred Stock - Outstanding Convertible Preferred Stock (Details) $ / shares in Units, $ in Thousands	Dec. 31, 2019USD ($)$ / sharesshares
Warrants and Rights Note Disclosure [Abstract]
Exercise Price Per share (in dollars per share) | $ / shares	$ 10.57
Warrants outstanding (in shares) | shares	215,291,000
Fair Value of Liability | $	$ 0

Warrants for Convertible Pref_4

Warrants for Convertible Preferred Stock - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		2 Months Ended		12 Months Ended
	Apr. 30, 2019	Feb. 28, 2018	Feb. 29, 2020	Feb. 28, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Mar. 01, 2019
Class of Warrant or Right [Line Items]
Issuance of convertible preferred stock (in shares)		7,884	213,876		213,876	4,934,231	7,884
Convertible securities, exercise price per share (in dollars per share)		$ 10.57		$ 10.57
Proceeds from stock issued	$ 40,000	$ 100		$ 2,300	$ 2,260	$ 64,804	$ 83
Shares issuable upon exercise of warrants (in shares)		430,588						215,291
(Income) expense on revaluation of warrants, less than					$ 0	(12)	12
Warrants expired, unexercised (in shares)				1,415
Maximum
Class of Warrant or Right [Line Items]
(Income) expense on revaluation of warrants, less than						$ (100)	$ 100

Convertible Preferred Stock - N

Convertible Preferred Stock - Narrative (Details) $ / shares in Units, $ in Thousands	Oct. 05, 2020shares	Apr. 30, 2019USD ($)$ / sharesshares	Feb. 28, 2018USD ($)shares	Feb. 29, 2020shares	Feb. 28, 2020USD ($)	Dec. 31, 2020USD ($)membervote$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)shares
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares) | shares	10,000,000					0	177,985,811
Issuance of convertible preferred stock (in shares) | shares			7,884	213,876		213,876	4,934,231	7,884
Shares issued, price per share (in dollars per share)		$ 13.20
Proceeds from stock issued | $		$ 40,000	$ 100		$ 2,300	$ 2,260	$ 64,804	$ 83
Conversion of convertible note into Series G-1 convertible preferred stock | $						0	25,133	$ 0
Liquidation value | $						$ 0	$ 210,610
Percentage of voting power prior to transaction						50.00%
Number of votes for each share of common stock held | vote						1
Number of members of Board of Directors | member						7
Minimum aggregate cash proceeds from sale of stock | $						$ 30,000
Second Lien Loan And Security Agreement | Convertible Debt
Class of Stock [Line Items]
Conversion of convertible note into Series G-1 convertible preferred stock | $		$ 25,100
Common Stock
Class of Stock [Line Items]
Conversion of convertible securities (in shares) | shares	17,797,026					17,797,026
Common Stock | Convertible Debt
Class of Stock [Line Items]
Conversion of convertible securities (in shares) | shares						2,561,484
Series A-1
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares) | shares							8,486,224
Dividend rate (in dollars per share)						$ 0.7672
Liquidation preference (in dollars per share)						9.59	$ 9.59
Liquidation value | $							$ 8,138
Liquidation preference, aggregate amount received per share (in dollars per share)						$ 28.77
Minimum shares outstanding for voting power (in shares) | shares						50,000
Number of Board of Director members entitled to be elected | member						1
Series B-1
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares) | shares							24,224,676
Dividend rate (in dollars per share)						$ 0.8456
Liquidation preference (in dollars per share)						10.57	$ 10.57
Liquidation value | $							$ 25,605
Liquidation preference, aggregate amount received per share (in dollars per share)						$ 31.71
Minimum shares outstanding for voting power (in shares) | shares						50,000
Number of Board of Director members entitled to be elected | member						2
Series C-1
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares) | shares							39,422,980
Dividend rate (in dollars per share)						$ 0.8456
Liquidation preference (in dollars per share)						10.57	$ 10.57
Liquidation value | $							$ 39,395
Liquidation preference, aggregate amount received per share (in dollars per share)						$ 31.71
Minimum shares outstanding for voting power (in shares) | shares						50,000
Number of Board of Director members entitled to be elected | member						2
Series D-1
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares) | shares							9,400,000
Dividend rate (in dollars per share)						$ 0.88
Liquidation preference (in dollars per share)						11	$ 11
Liquidation value | $							$ 10,340
Liquidation preference, aggregate amount received per share (in dollars per share)						33
Series E-1
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares) | shares							9,230,768
Dividend rate (in dollars per share)						1.04
Liquidation preference (in dollars per share)						13	$ 13
Liquidation value | $							$ 12,000
Liquidation preference, aggregate amount received per share (in dollars per share)						39
Series F-1
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares) | shares							37,878,787
Dividend rate (in dollars per share)						1.056
Liquidation preference (in dollars per share)						$ 13.20	$ 13.20
Period to determine Additional Preference						1 year
Liquidation value | $							$ 50,000
Liquidation preference, aggregate amount received per share (in dollars per share)						$ 39.60
Series F-1 | Equity to or greater than $250.0 million, but less than $300.0 million
Class of Stock [Line Items]
Additional preference per share (in dollars per share)						3.30
Series F-1 | Equity to or greater than $300.0 million but less than $350.0 million
Class of Stock [Line Items]
Liquidation preference (in dollars per share)						5
Series F-1 | Equal to or greater than $350.0 million
Class of Stock [Line Items]
Liquidation preference (in dollars per share)						$ 6.60
Liquidation value | $						$ 350,000
Series F-1 | Minimum | Equity to or greater than $250.0 million, but less than $300.0 million
Class of Stock [Line Items]
Additional preference, liquidation transaction threshold | $						250,000
Series F-1 | Minimum | Equity to or greater than $300.0 million but less than $350.0 million
Class of Stock [Line Items]
Liquidation value | $						300,000
Series F-1 | Maximum | Equity to or greater than $250.0 million, but less than $300.0 million
Class of Stock [Line Items]
Liquidation value | $						300,000
Series F-1 | Maximum | Equity to or greater than $300.0 million but less than $350.0 million
Class of Stock [Line Items]
Liquidation value | $						$ 350,000
Series G-1
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares) | shares							49,342,376
Issuance of convertible preferred stock (in shares) | shares		3,030,296
Dividend rate (in dollars per share)						$ 1.056
Liquidation preference (in dollars per share)						13.20	$ 13.20
Liquidation value | $							$ 65,132
Liquidation preference, aggregate amount received per share (in dollars per share)						$ 39.60
Minimum shares outstanding for voting power (in shares) | shares						50,000
Number of Board of Director members entitled to be elected | member						1
Conversion ratio						1.15
Series G-1 | Second Lien Loan And Security Agreement | Convertible Debt
Class of Stock [Line Items]
Shares issued upon conversion of debt (in shares) | shares		1,903,935
Conversion price per share (in dollars per share)		$ 13.20

Convertible Preferred Stock - S

Convertible Preferred Stock - Schedule of Convertible Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2020	Oct. 05, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Number of Shares Authorized (in shares)	0	10,000,000	177,985,811
Number of Shares Issued (in shares)	0		17,583,150
Number of Shares Outstanding (in shares)	0		17,583,150	12,648,919	12,641,035
Carrying Value	$ 0		$ 205,339	$ 140,535	$ 140,452
Liquidation Value	$ 0		$ 210,610
Series A-1
Class of Stock [Line Items]
Number of Shares Authorized (in shares)			8,486,224
Number of Shares Issued (in shares)			848,595
Number of Shares Outstanding (in shares)			848,595
Carrying Value			$ 8,135
Liquidation Preference per Share (in dollars per share)	$ 9.59		$ 9.59
Liquidation Value			$ 8,138
Series B-1
Class of Stock [Line Items]
Number of Shares Authorized (in shares)			24,224,676
Number of Shares Issued (in shares)			2,422,444
Number of Shares Outstanding (in shares)			2,422,444
Carrying Value			$ 23,130
Liquidation Preference per Share (in dollars per share)	10.57		$ 10.57
Liquidation Value			$ 25,605
Series C-1
Class of Stock [Line Items]
Number of Shares Authorized (in shares)			39,422,980
Number of Shares Issued (in shares)			3,726,974
Number of Shares Outstanding (in shares)			3,726,974
Carrying Value			$ 37,306
Liquidation Preference per Share (in dollars per share)	10.57		$ 10.57
Liquidation Value			$ 39,395
Series D-1
Class of Stock [Line Items]
Number of Shares Authorized (in shares)			9,400,000
Number of Shares Issued (in shares)			939,979
Number of Shares Outstanding (in shares)			939,979
Carrying Value			$ 10,268
Liquidation Preference per Share (in dollars per share)	11		$ 11
Liquidation Value			$ 10,340
Series E-1
Class of Stock [Line Items]
Number of Shares Authorized (in shares)			9,230,768
Number of Shares Issued (in shares)			923,049
Number of Shares Outstanding (in shares)			923,049
Carrying Value			$ 11,896
Liquidation Preference per Share (in dollars per share)	13		$ 13
Liquidation Value			$ 12,000
Series F-1
Class of Stock [Line Items]
Number of Shares Authorized (in shares)			37,878,787
Number of Shares Issued (in shares)			3,787,878
Number of Shares Outstanding (in shares)			3,787,878
Carrying Value			$ 49,800
Liquidation Preference per Share (in dollars per share)	13.20		$ 13.20
Liquidation Value			$ 50,000
Series G-1
Class of Stock [Line Items]
Number of Shares Authorized (in shares)			49,342,376
Number of Shares Issued (in shares)			4,934,231
Number of Shares Outstanding (in shares)			4,934,231
Carrying Value			$ 64,804
Liquidation Preference per Share (in dollars per share)	$ 13.20		$ 13.20
Liquidation Value			$ 65,132

Stockholders' Equity (Deficit_2

Stockholders' Equity (Deficit) - Narrative (Details)	1 Months Ended		2 Months Ended	12 Months Ended
	Jan. 31, 2021shares	Sep. 30, 2020USD ($)shares	Mar. 15, 2021shares	Dec. 31, 2020USD ($)vote$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Oct. 05, 2020shares	Dec. 31, 2017$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized (in shares)				200,000,000	240,000,000		200,000,000
Dividends declared | $				$ 0
Number of votes for each share of common stock held | vote				1
Stock retired during period (shares)					414
Shares reserved for future issuance (in shares)				6,877,197	21,155,368
Options exercised, aggregate intrinsic value | $				$ 2,000,000	$ 200,000	$ 100,000
Options outstanding, weighted average exercise price (in dollars per share) | $ / shares				$ 4.72	$ 1.66	$ 1.51		$ 1.52
Options exercisable, weighted average exercise price (in dollars per share) | $ / shares				$ 4.72	$ 1.66
Options outstanding, aggregate intrinsic value | $				$ 188,000,000	$ 10,900,000
Options exercisable, aggregate intrinsic value | $				188,000,000	10,900,000
Options vested and expenses to vest, intrinsic value | $				$ 81,700,000	$ 7,600,000
Repurchase of early exercised common stock options (in shares)				10,000	9,147
Common stock, shares repurchased, less than | $				$ 100,000	$ 100,000
Aggregate exercise price of shares subject to repurchase | $				$ 600,000	$ 300,000
Options granted (in shares)				1,466,071	1,078,957	255,900
Fair value of stock options granted (in dollars per share) | $ / shares				$ 3.78	$ 1.79	$ 0.70
Stock-based compensation capitalized into inventory | $				$ 300,000	$ 0	$ 0
Unrecognized compensation costs | $				14,800,000
Fair value of shares vested | $				$ 1,900,000	$ 300,000	$ 400,000
Stock Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance (in shares)				9,842,151
2000 Stock Plan | Directors, Employees And Consultants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance (in shares)				0	0
Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock, percentage of fair market value, greater than				100.00%
Award vesting period				4 years
Award expiration period, not more than				10 years
Shares subject to repurchase (in shares)				355,677	199,810
Weighted-average period for recognition of compensation costs				2 years 3 months 10 days
Options to purchase common stock | Share-based Payment Arrangement, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rate				25.00%
Options to purchase common stock | Share-based Payment Arrangement, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rate				25.00%
Options to purchase common stock | Share-based Payment Arrangement, Tranche Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rate				25.00%
Options to purchase common stock | Share-based Payment Arrangement, Tranche Four
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rate				25.00%
Options to purchase common stock | Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)			8,600
Options to purchase common stock | Over 10% Shareholder
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock, percentage of fair market value, greater than				110.00%
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance (in shares)		720,000		720,000	0
Purchase price of common stock, percentage of fair market value, greater than		85.00%
Payroll deduction rate, percentage of base compensation		15.00%
Maximum number of shares available per employee (in shares)		2,500
Maximum value of shares available per employee | $		$ 25,000
Shares issued in period (in shares)				0
Unrecognized compensation costs | $				$ 2,300,000
Weighted-average period for recognition of compensation costs				4 months 24 days
Employee Stock Purchase Plan | Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in shares from automatic increase provision (in shares)	356,937

Stockholders' Equity (Deficit_3

Stockholders' Equity (Deficit) - Shares Reserved for Future Issuance (Details) - shares	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Shares reserved for future issuance (in shares)	6,877,197		21,155,368
Common stock options issued and outstanding
Class of Stock [Line Items]
Shares reserved for future issuance (in shares)	2,923,403		3,279,324
Common stock available for future grants
Class of Stock [Line Items]
Shares reserved for future issuance (in shares)	3,233,794		77,603
Common stock available for ESPP
Class of Stock [Line Items]
Shares reserved for future issuance (in shares)	720,000	720,000	0
Warrants to purchase Series C-1 convertible preferred stock
Class of Stock [Line Items]
Shares reserved for future issuance (in shares)	0		215,291
Series A-1
Class of Stock [Line Items]
Shares reserved for future issuance (in shares)	0		848,595
Series B-1
Class of Stock [Line Items]
Shares reserved for future issuance (in shares)	0		2,422,444
Series C-1
Class of Stock [Line Items]
Shares reserved for future issuance (in shares)	0		3,726,974
Series D-1
Class of Stock [Line Items]
Shares reserved for future issuance (in shares)	0		939,979
Series E-1
Class of Stock [Line Items]
Shares reserved for future issuance (in shares)	0		923,049
Series F-1
Class of Stock [Line Items]
Shares reserved for future issuance (in shares)	0		3,787,878
Series G-1
Class of Stock [Line Items]
Shares reserved for future issuance (in shares)	0		4,934,231

Stockholders' Equity (Deficit_4

Stockholders' Equity (Deficit) - Options Vested and Expected to Vest (Details)	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Number of Shares
Options vested (in shares) | shares	1,219,241
Options vested and expected to vest (in shares) | shares	2,923,403
Weighted Average Exercise Price
Options vested (in dollars per share) | $ / shares	$ 2.03
Options vested and expected to vest (in dollars per share) | $ / shares	$ 4.72
Weighted Average Contractual Life (in Years)
Options vested	5 years 2 months 23 days
Options vested and expected to vest	7 years 7 months 17 days

Stockholders' Equity (Deficit_5

Stockholders' Equity (Deficit) - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Shares Available for Grant
Options granted (in shares)	(1,466,071)	(1,078,957)	(255,900)
Options canceled (in shares)	76,952	35,809	31,201
Number of Shares
Balance, beginning of period (in shares)	3,279,324	2,626,494	2,419,948
Options granted (in shares)	1,466,071	1,078,957	255,900
Options exercised (in shares)	(1,745,040)	(390,318)	(18,153)
Options canceled (in shares)	(76,952)	(35,809)	(31,201)
Balance, end of period (in shares)	2,923,403	3,279,324	2,626,494
Weighted Average Exercise Price
Balance, beginning of period (in dollars per share)	$ 1.66	$ 1.51	$ 1.52
Options granted (in dollars per share)	7.73	1.93	1.37
Options exercised (in dollars per share)	1.55	1.35	1.68
Options canceled (in dollars per share)	3.55	1.39	1.53
Balance, end of period (in dollars per share)	$ 4.72	$ 1.66	$ 1.51
2000 Stock Plan
Shares Available for Grant
Options canceled (in shares)	68,884	35,309	11,201
Number of Shares
Options canceled (in shares)	(68,884)	(35,309)	(11,201)
Options to purchase common stock
Shares Available for Grant
Balance, beginning of period (in shares)	77,603	382,679	125,199
Additional shares reserved (in shares)	4,553,378	738,572	502,179
Balance, end of period (in shares)	3,233,794	77,603	382,679

Stockholders' Equity (Deficit_6

Stockholders' Equity (Deficit) - Valuation Assumptions (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	$ 0	$ 0	$ 0
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average expected term (in years)			6 years 3 months 18 days
Volatility, minimum	40.00%	47.10%
Volatility, maximum	44.70%	49.70%
Volatility			46.00%
Dividend yield	$ 0	$ 0	$ 0
Stock options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average expected term (in years)	5 years	5 years 3 months 18 days
Risk-free interest rate	0.20%	1.40%	2.40%
Stock options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days
Risk-free interest rate	1.70%	1.80%	2.90%
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average expected term (in years)	7 months 6 days
Volatility, minimum	67.70%
Volatility, maximum	68.20%
Risk-free interest rate	0.10%
Dividend yield	$ 0

Stockholders' Equity (Deficit_7

Stockholders' Equity (Deficit) - Total Stock-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 3,197	$ 364	$ 366
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2,055	364	366
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,142	0	0
Cost of goods sold
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	39	30	18
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	398	64	62
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,760	$ 270	$ 286

Net Loss per Share Attributab_3

Net Loss per Share Attributable to Common Stockholders - Computation of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator
Net loss attributable to common stockholders									$ (32,231)	$ (20,703)	$ (18,479)
Denominator
Weighted-average common stock outstanding (in shares)									10,341,809	1,796,233	1,706,654
Less: weighted-average common shares subject to repurchase (in shares)									(156,968)	(20,123)	(31,875)
Weighted-average shares used in computing net loss per share attributable to common stockholder, basic and diluted (in shares)									10,184,841	1,776,110	1,674,779
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.27)	$ (1.37)	$ (6.15)	$ (3.76)	$ (2.48)	$ (2.41)	$ (3.24)	$ (3.61)	$ (3.16)	$ (11.66)	$ (11.03)

Net Loss per Share Attributab_4

Net Loss per Share Attributable to Common Stockholders - Excluded Potentially Dilutive Securities Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted weighted average shares outstanding (in shares)	0	17,583,150	12,648,919
Convertible preferred stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted weighted average shares outstanding (in shares)	0	215,291	215,291
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted weighted average shares outstanding (in shares)	2,923,403	3,279,324	2,626,494
Unvested early exercised common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted weighted average shares outstanding (in shares)	355,677	199,810	26,852
Conversion of convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted weighted average shares outstanding (in shares)	0	0	0
Common stock available for ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted weighted average shares outstanding (in shares)	47,174	0	0

Segment Information - Narrative

Segment Information - Narrative (Details) - segment	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Concentration Risk [Line Items]
Number of reportable segments	1
Number of operating segments	1
Revenue from Contract with Customer Benchmark | Geographic Concentration Risk | GERMANY
Concentration Risk [Line Items]
Customer concentration risk percentage	17.00%	22.00%	37.00%

Segment Information - Revenue b

Segment Information - Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 9,830	$ 10,612	$ 3,673	$ 8,618	$ 10,347	$ 9,104	$ 7,366	$ 5,778	$ 32,733	$ 32,595	$ 20,004
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									16,189	10,704	563
Europe, Middle-East and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									13,808	18,364	16,175
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									2,687	3,227	3,115
Other International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									$ 49	$ 300	$ 151

Segment Information - Long-Live

Segment Information - Long-Lived Assets by Geographical Area (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 1,474	$ 902
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	1,437	852
Europe, Middle-East and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	29	40
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 8	$ 10

Employee Benefit Plan (Details)

Employee Benefit Plan (Details) - USD ($)	12 Months Ended	279 Months Ended
	Dec. 31, 2020	Dec. 31, 2020
Retirement Benefits [Abstract]
Maximum employee contribution percentage	100.00%
Contributions made by the Company since inception		$ 0

Related Party Disclosures (Deta

Related Party Disclosures (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transactions [Abstract]
Payments for consulting services, less than	$ 0.1	$ 0.1	$ 0.1

Selected Quarterly Financial _3

Selected Quarterly Financial Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue	$ 9,830	$ 10,612	$ 3,673	$ 8,618	$ 10,347	$ 9,104	$ 7,366	$ 5,778	$ 32,733	$ 32,595	$ 20,004
Gross Profit	7,078	7,462	1,012	5,650	7,337	6,407	4,953	3,717	21,202	22,414	12,286
Net loss	$ (9,297)	$ (3,860)	$ (11,911)	$ (7,163)	$ (4,669)	$ (4,335)	$ (5,571)	$ (6,128)	$ (32,231)	$ (20,703)	$ (18,479)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.27)	$ (1.37)	$ (6.15)	$ (3.76)	$ (2.48)	$ (2.41)	$ (3.24)	$ (3.61)	$ (3.16)	$ (11.66)	$ (11.03)

Subsequent Events (Details)

Subsequent Events (Details) - $ / shares	2 Months Ended	12 Months Ended
	Mar. 15, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Subsequent Event [Line Items]
Options granted (in shares)		1,466,071	1,078,957	255,900
Options granted (in dollars per share)		$ 7.73	$ 1.93	$ 1.37
Restricted Stock Units (RSUs) | Subsequent Event
Subsequent Events [Abstract]
Awards granted (in shares)	6,300
Subsequent Event [Line Items]
Awards granted (in shares)	6,300
Stock options | Subsequent Event
Subsequent Event [Line Items]
Options granted (in shares)	8,600
Options granted (in dollars per share)	$ 62.34