REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Shareholders and Board of Trustees of FlexShares Trust:

In planning and performing our audits of the financial statements
of FlexShares Trust (the "Trust"), comprised of FlexShares US
Quality Low Volatility Index Fund, FlexShares Developed Markets
ex-US Quality Low Volatility Index Fund, FlexShares Emerging Markets
Quality Low Volatility Index Fund, FlexShares Morningstar US Market
Factor Tilt Index Fund, FlexShares Morningstar Developed Markets ex-US
Factor Tilt Index Fund, FlexShares Morningstar Emerging Markets Factor
Tilt Index Fund, FlexShares US Quality Large Cap Index Fund, FlexShares
STOXX US ESG Select Index Fund, FlexShares STOXX Global ESG Select Index
Fund, FlexShares ESG & Climate US Large Cap Core Index Fund,
FlexShares ESG & Climate Developed Markets ex-US Core Index Fund,
FlexShares ESG & Climate Emerging Markets Core Index Fund, FlexShares
Morningstar Global Upstream Natural Resources Index Fund, FlexShares
STOXX Global Broad Infrastructure Index Fund, FlexShares Global Quality
Real Estate Index Fund, FlexShares Real Assets Allocation Index Fund,
FlexShares Quality Dividend Index Fund, FlexShares Quality Dividend
Defensive Index Fund, FlexShares International Quality Dividend Index
Fund, FlexShares International Quality Dividend Defensive Index Fund,
FlexShares International Quality Dividend Dynamic Index Fund, FlexShares
iBoxx 3-Year Target Duration TIPS Index Fund, FlexShares iBoxx 5-Year
Target Duration TIPS Index Fund, FlexShares Disciplined Duration MBS
Index Fund, FlexShares Credit-Scored US Corporate Bond Index Fund,
FlexShares Credit-Scored US Long Corporate Bond Index Fund, FlexShares
High Yield Value-Scored Bond Index Fund, FlexShares ESG & Climate
Investment Grade Corporate Core Index Fund, FlexShares Ultra-Short Income
Fund (formerly FlexShares Ready Access Variable Income Fund), and FlexShares
Core Select Bond Fund as of and for the year ended October 31, 2023,
in accordance with the standards of the Public Company Accounting Oversight
Board (United States) (PCAOB), we considered the Trust's internal control
over financial reporting, including controls over safeguarding securities,
as a basis for designing our auditing procedures for the purpose of
expressing our opinion on the financial statements and to comply with
the requirements of Form N-CEN, but not for the purpose of expressing
an opinion on the effectiveness of the Trust's internal control over
financial reporting. Accordingly, we express no such opinion.

The management of the Trust is responsible for establishing and maintaining
effective internal control over financial reporting. In fulfilling this
responsibility, estimates and judgments by management are required to assess
the expected benefits and related costs of controls. A company's internal
control over financial reporting is a process designed to provide reasonable
assurance regarding the reliability of financial reporting and the preparation
of financial statements for external purposes in accordance with generally
accepted accounting principles. A company's internal control over financial
reporting includes those policies and procedures that (1) pertain to the
maintenance of records that, in reasonable detail, accurately and
fairly reflect the transactions and dispositions of the assets of
the company; (2) provide reasonable assurance that transactions are recorded
as necessary to permit preparation of financial statements in accordance
with generally accepted accounting principles, and that receipts and
expenditures of the company are being made only in accordance with
authorizations of management and directors of the company; and
(3) provide reasonable assurance regarding prevention or timely detection
of unauthorized acquisition, use, or disposition of a company's assets
that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial
reporting may not prevent or detect misstatements. Also, projections
of any evaluation of effectiveness to future periods are subject to
the risk that controls may become inadequate because of changes in
conditions, or that the degree of compliance with the policies or
procedures may deteriorate.

A deficiency in internal control over financial reporting exists
when the design or operation of a control does not allow management
or employees, in the normal course of performing their assigned
functions, to prevent or detect misstatements on a timely basis.
A material weakness is a deficiency, or a combination of
deficiencies, in internal control over financial reporting,
such that there is a reasonable possibility that a material
misstatement of the company's annual or interim financial statements
will not be prevented or detected on a timely basis.

Our consideration of the Trust's internal control over financial
reporting was for the limited purpose described in the first
paragraph and would not necessarily disclose all deficiencies in
internal control that might be material weaknesses under standards
established by the PCAOB. However, we noted no deficiencies in the
Trust's internal control over financial reporting and its operation,
including controls for safeguarding securities, that we consider
to be a material weakness, as defined above, as of October 31, 2023.

This report is intended solely for the information and use of
management and the Board of Trustees of the Trust and the
Securities and Exchange Commission and is not intended to be
and should not be used by anyone other than these specified parties.

/s/ DELOITTE & TOUCHE LLP
Chicago, Illinois
December 20, 2023