Summary of Significant Accounting Policies | 2. Summary of Significant Accounting Policies COVID-19 and CARES Act 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 have imposed “shelter-in-place” orders, quarantines and other restrictions. In the United States, governmental authorities have recommended, and in certain cases required, that elective, specialty and other procedures and appointments, be suspended or canceled. Similarly, 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, work stoppages, slowdowns and delays, travel restrictions and cancellation of events. These orders and restrictions have significantly decreased the number of procedures performed using the Company’s products and otherwise negatively impacted operations. In response to the impact of COVID-19, the Company implemented a variety of measures intended to help manage through the impact and position it to resume operations quickly and efficiently once these restrictions are lifted. Some of these measures include: adapting, expanding and improving various sales, physician outreach and training programs to address the current environment; producing approximately four months’ worth of inventory before temporarily suspending production and executing a work from home strategy for administrative functions. The impact of COVID-19 is changing daily and cannot be predicted. As a result, the Company expects the pandemic to continue to negatively impact its business, financial condition and results of operations. On March 27, 2020, the President signed into law the “Coronavirus Aid, Relief, and Economic Security (CARES) Act.” The CARES Act, among other things, includes provisions relating to refundable payroll tax credits, deferment of employer side social security payments, net operating loss carryback periods, alternative minimum tax credit refunds, modifications to the net interest deduction limitations, increased limitations on qualified charitable contributions, and technical corrections to tax depreciation methods for qualified improvement property. The Company currently may be eligible but has not taken advantage of the payroll protection program, emergency grants and business loans under the CARES Act. The Company expects to monitor the impact that the CARES Act may have on its business, financial condition, results of operations, or liquidity. Basis of Presentation of Unaudited Interim Condensed Consolidated Financial Statements The accompanying condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Certain prior year reported amounts have been reclassified to conform with the 2020 presentation. The interim condensed consolidated balance sheet as of June 30, 2020, the condensed consolidated statements of operations, m ezzanine equity and stockholders’ deficit, filed pursuant to Rule 424(b)(4) with the U.S. Securities and Exchange Commission on May 26, 2020 Principles of Consolidation In May 2020, the Company formed Inari Medical International, Inc., a wholly-owned subsidiary incorporated in Delaware. All intercompany balances and transactions have been eliminated in consolidation. Management Estimates The preparation of financial statements in conformity with U.S. 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 financial statements and the reported amounts of revenue and expenses during the reporting period. Significant estimates and assumptions made in the accompanying financial statements include, but are not limited to the collectability of receivables, valuation of inventory, the fair value of common stock warrants, the fair value of preferred stock warrant liabilities, the fair value of stock options, recoverability of the Company’s net deferred tax assets, and related valuation allowance and certain accruals. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could materially differ from those estimates. JOBS Act Accounting Election As an emerging growth company under the Jumpstart Our Business Startups Act of 2012 ("the JOBS Act"), the Company is eligible to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. the Company has elected to take advantage of the extended transition period for adopting new or revised accounting standards that have different effective dates for public and private companies until such time as those standards apply to private companies. Cash, Cash Equivalents and Restricted Cash The Company considers cash on hand, cash in demand deposit accounts including money market funds, and instruments with a maturity date of 90 days or less at date of purchase to be cash and cash equivalents. The Company maintains its cash, cash equivalent and restricted cash balances with banks. Under the Dodd-Frank Wall Street Reform and Consumer Protection Act, deposits of up to $250,000 at FDIC-insured institutions are covered by FDIC insurance. At times, deposits may be in excess of the FDIC insurance limit; however, management does not believe the Company is exposed to any significant related credit risk. Restricted cash as of June 30, 2020 and December 31, 2019 consisted of a cash secured letter of credit in the amount of $338,000 representing collateral for the Company’s facility lease. Restricted cash additionally included as of June 30, 2020 and December 31, 2019, a compensating balance of $50,000 to secure the Company’s corporate purchasing cards. Accounts Receivable, net Trade accounts receivable are recorded at the invoiced amount, net of any allowance for doubtful accounts. Any allowance for doubtful accounts is developed based upon several factors including the customers’ credit quality, historical write-off experience and any known specific issues or disputes which exist as of the balance sheet date. Account receivable balances are written off against the allowance after appropriate collection efforts are exhausted. The allowance for doubtful accounts was $146,000 and $62,000 as of June 30, 2020 and December 31, 2019, respectively, and no accounts receivable write offs were recognized during the three and six months ended June 30, 2020 and 2019. Despite the Company’s efforts to minimize credit risk exposure, customers could be adversely affected if future economic and industry trends, including those related to COVID-19, change in such a manner as to negatively impact their cash flows. The full effects of COVID-19 on the Company’s customers are highly uncertain and cannot be predicted. As a result, the Company’s future collection experience can differ significantly from historical collection trends. If the Company’s clients experience a negative impact on their cash flows, it could have a material adverse effect on the Company’s results of operations and financial condition. Inventories, net The Company values inventory at the lower of the actual cost to purchase or manufacture the inventory or net realizable value for such inventory. Cost, which includes material, labor and overhead costs, is determined on the first-in, first out method, or FIFO. The Company regularly reviews inventory quantities in process and on hand, and when appropriate, records a provision for obsolete and excess inventory. The Company writes down inventory that has become obsolete, inventory that has a cost basis in excess of its expected net realizable value and inventory in excess of expected requirements based on future demand and as compared to remaining shelf life. The estimate of excess quantities is subjective and primarily dependent on the Company’s estimates of future demand for a particular product. If the estimate of future demand is inaccurate based on actual sales, the Company may increase the write down for excess inventory for that component and record a charge to inventory impairment in the accompanying condensed consolidated statement of operations and comprehensive income (loss). Property and Equipment Property and equipment are stated at cost. Additions and improvements that extend the lives of the assets are capitalized while expenditures for repairs and maintenance are expensed as incurred. Depreciation is provided using the straight-line method over the estimated useful lives of the assets, ranging from three to seven years. Leasehold improvements are depreciated over the shorter of the useful life of the improvement or the lease term, including renewal periods that are reasonably assured. Upon sale or disposition of property and equipment, any gain or loss is included in the accompanying statement of operations. Deferred Initial Public Offering Costs Specific incremental legal, accounting and other fees and costs directly attributable to a proposed or actual offering of securities may properly be deferred and charged against the gross proceeds of the offering. As of December 31, 2019, there were approximately $1,382,000 of offering costs, primarily consisting of legal, accounting and printing fees, which were capitalized in other non-current assets on the balance sheet. In May 2020, upon the closing of the IPO, total deferred costs of approximately $3,701,000 were offset against the Company’s IPO proceeds. Impairment of Long-lived Assets The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparing the carrying amount to the future net undiscounted cash flows which the assets are expected to generate. If such assets are considered impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the projected discounted future net cash flows arising from the asset. The Company has not identified any such impairment losses to date. Fair Value of Financial Instruments The Company’s cash, cash equivalents and restricted cash, accounts receivable, accounts payable and accrued liabilities approximate their fair value due to their liquidity or short maturities. Management believes that its long term debt bears interest at the prevailing market rates for instruments with similar characteristics; accordingly, the carrying value of this instrument approximates its fair value as of June 30, 2020 and December 31, 2019. The Company measures and records certain financial assets and liabilities at fair value on a recurring basis. U.S. GAAP provides a fair value hierarchy that distinguishes between (i) market participant assumptions developed based on market data obtained from independent sources (observable inputs) and (ii) an entity’s own assumptions about market participant assumptions developed based on the best information available in the circumstances (unobservable inputs). The fair value hierarchy consists of three broad levels. • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices 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 assets or liabilities. • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of assets or liabilities. See Note 3 for further information. Convertible Preferred Stock Warrant Liability The Company has accounted for its freestanding warrants to purchase shares of the Company’s convertible preferred stock as liabilities at fair value upon issuance primarily because the preferred shares underlying the warrants contain contingent redemption features outside the control of the Company. The warrants are subject to remeasurement at each balance sheet date and any change in fair value is recognized as the change in fair value of warrant liability and recorded to other expense in the statements of operations. The carrying value of the warrants continued to be adjusted until the completion of the IPO, which occurred in May 2020. At that time, the preferred stock warrant liability was adjusted to fair value and reclassified to additional paid-in capital, a component of stockholders’ equity (deficit) (see Note 3). Revenue Recognition On January 1, 2019, the Company adopted Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers, Under ASC 606, revenue is recognized when a customer obtains control of promised goods or services, in an amount that reflects the 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: (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 a performance obligation. Product sales of the FlowTriever and ClotTriever systems are made to hospitals in the United States utilizing the Company’s direct sales force. Revenue is comprised of product revenue net of returns, administration fees and sales rebates. Performance Obligation —The Company has revenue arrangements that consist of a single performance obligation, delivery of the Company’s products. The satisfaction of this performance obligation occurs with the transfer of control of the Company’s product to its customers, either upon shipment or delivery of the product. Revenue is measured as the amount of consideration the Company expects to receive in exchange for transferring goods. The amount of revenue that is recognized is based on the transaction price, which represents the invoiced amount and includes estimates of variable consideration such as rebate and administrative fees, where applicable. The Company provides a 30-day unconditional right of return period. The Company establishes estimated provisions for returns at the time of sale based on historical experience. Historically, the actual product returns have been immaterial to the Company’s financial statements. Assuming all other revenue recognition criteria have been met, the Company recognizes revenue for arrangements where the Company has satisfied its performance obligation of delivering the product. For sales where the Company’s sales representatives hand deliver products directly to the hospital, control of the products transfers to the customer upon such hand delivery. For sales where products are shipped, control of the products transfers either upon shipment or delivery of the products to the customer, depending on the shipping terms and conditions. As of June 30, 2020 and December 31, 2019, the Company recorded $302,000 and $330,000, respectively, of unbilled receivables, which are included in accounts receivable, net, in the accompanying balance sheet. For both the three months ended June 30, 2020 and 2019, 40% of revenue was derived from the sale of ClotTriever products, and 60% of revenue was derived from the sale of FlowTriever products. For the six months ended June 30, 2020 and 2019, 38% and 39% of revenue was derived from the sale of ClotTriever products, respectively, and 62% and 61% of revenue was derived from the sale of FlowTriever products, respectively. The Company offers payment terms to its customer of less than three months and these terms do not include a significant financing component. The Company excludes taxes assessed by governmental authorities on revenue-producing transactions from the measurement of the transaction price. The Company offers its standard warranty to all customers and no warranties are available for sale on a standalone basis. The Company’s warranty provides that its products are free of material defects and conform to specifications, and offer to repair, replace or refund the purchase price of defective products. This assurance does not constitute a service and is not considered a separate performance obligation. The Company estimates warranty liabilities at the time of revenue recognition and records it as a charge to cost of goods sold. Costs associated with product sales include commissions and are recorded in selling, general and administrative expenses. The Company applies the practical expedient and recognizes commissions as expense when incurred because the amortization period is less than one year. Cost of Goods Sold Cost of goods sold consists primarily of the cost of raw materials, components, direct labor and manufacturing overhead. Overhead costs include the cost of quality assurance, material procurement, inventory control, facilities, equipment and operations supervision and management, including stock-based compensation. Cost of goods sold also includes depreciation expense for production equipment and certain direct costs such as shipping costs and royalty expense. Shipping Costs Shipping costs billed to customers are not included in revenue, and are reported as a reduction of costs of goods sold. Advertising Costs Advertising costs are charged to operations as incurred. Advertising costs were $74,000 and $6,000 for the three months ended June 30, 2020 and 2019, respectively and $111,000 and $34,000 for the six months ended June 30, 2020 and 2019, respectively. Advertising costs are included in selling, general and administrative expenses in the accompanying statements of operations. Research and Development Research and development costs are expensed as incurred and include the costs to design, develop, test, deploy and enhance new and existing products. Research and development costs also include expenses associated with clinical studies, registries and sponsored research. These costs include direct salary and employee benefit related costs for research and development personnel, costs for materials used and costs for outside services. Patent-related Expenditures Expenditures related to patent research and applications, which are primarily legal fees, are expensed as incurred and are included in selling, general and administrative expenses in the accompanying statements of operations. Stock-based Compensation The Company’s employee and non-employee share-based awards result in a cost that is measured at fair value on the awards’ grant date, based on the estimated number of awards that are expected to vest. Stock-based compensation is recognized over the service period. Income Taxes The Company uses the asset and liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and the tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. Management assesses the likelihood that the resulting deferred tax assets will be realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. Due to the Company’s historical operating performance and the recorded cumulative net losses in prior fiscal periods, the net deferred tax assets have been fully offset by a valuation allowance. The Company recognizes uncertain income tax positions at the largest amount that is more likely than not to be sustained upon audit by the relevant taxing authority. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. Changes in recognition or measurement are reflected in the period in which judgment occurs. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of provision for income taxes. Foreign Currency Transactions Certain vendors are paid in currencies other than the US dollar. Transaction gains and losses are included in selling, general and administrative expenses. Comprehensive Income (Loss) The Company’s net income (loss) equaled comprehensive income (loss) for the three and six months ended June 30, 2020 and 2019. Net Income (Loss) per Share of Common Stock Basic net income (loss) per share is computed by dividing the net income (loss) attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period, without consideration for potential dilutive common shares. Diluted net income (loss) per share is computed by dividing the net income (loss) attributable to common stockholders by the weighted average number of shares of common stock and potentially dilutive securities outstanding for the period. For purposes of the diluted net income (loss) per share calculation, redeemable convertible preferred stock and warrants, and common stock options are considered to be potentially dilutive securities. For the periods the Company is in a net loss position, basic net loss per share is the same as diluted net loss per share as the inclusion of all potential dilutive common shares would have been anti-dilutive. The Company allocates no loss to participating securities because they have no contractual obligation to share in the losses of the Company. The shares of the Company’s convertible preferred stock participate in any dividends declared by the Company and are therefore considered to be participating securities. Segment Reporting Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its Chief Executive Officer. The Company has determined it operates in one segment - the development and commercialization of innovative and minimally invasive mechanical thrombectomy devices to treat thromboembolism in the venous system. Geographically, we sell to hospitals in the United States. Segment information is consistent with how management reviews the business, makes investing and resource allocation decisions and assesses operating performance. Recently Adopted Accounting Pronouncements In June 2018, the FASB issued ASU No. 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting Recent Accounting Pronouncements In February 2017, the FASB issued ASU 2017-02, Leases In June 2016, the FASB issued ASU 2016-13 “ Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments |