Washington, D.C. 20549


Under the Securities Exchange Act of 1934
(Amendment No. 4)*

TriMas Corp.

(Name of Issuer)


(Title of Class of Securities)


(CUSIP Number)

DECEMBER 31, 2020

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant
to which this Schedule is filed:
[ X ] Rule 13d-1(b)
[ ] Rule 13d-1(c)
[ ] Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 896215209


     1. Names of Reporting Persons.
I.R.S. Identification Nos. of above persons (entities only).

                Fiduciary Management, Inc.


 2.  Check the Appropriate Box if a Member of a Group (See Instructions)




 3. SEC Use Only


 4. Citizenship or Place of Organization

                100 East Wisconsin Avenue
                Suite 2200
                Milwaukee, WI 53202
                United States

          NUMBER OF         5     SOLE VOTING POWER
           SHARES                                               2,698,081

        BENEFICIALLY        ----------------------------------------------------
          OWNED BY          6     SHARED VOTING POWER

         REPORTING          ----------------------------------------------------
           PERSON           7     SOLE DISPOSITIVE POWER
            WITH                                                3,177,614

                            8     SHARED DISPOSITIVE POWER


 9. Aggregate Amount Beneficially Owned by Each Reporting Person



 10. Check if the Aggregate Amount in Row (9) Excludes Certain Shares
     (See Instructions)


 11. Percent of Class Represented by Amount in Row (9)


 12. Type of Reporting Person (See Instructions)


Item 1.

 (a)    TriMas Corp.

 (b)    39400 Woodward Avenue
        Suite 130
        Bloomfield Hills, MI  48304
        United States

Item 2.

 (a)    Fiduciary Management, Inc.

 (b)    100 East Wisconsin Avenue
        Suite 2200
        Milwaukee, WI 53202
        United States

 (c)    Wisconsin

 (d)    Common Stock

 (e)    896215209

Item 3.

 (a) [   ] Broker or dealer registered under section 15
           of the Act (15 U.S.C. 78o).

 (b) [   ] Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c).

 (c) [   ] Insurance company as defined in section
           3(a)(19) of the Act (15 U.S.C. 78c).

 (d) [   ] Investment company registered under section 8
           of the Investment Company Act of 1940
           (15 U.S.C 80a-8).

 (e) [ X ] An investment adviser in accordance with 240.13d-1(b)(1)(ii)(E);

 (f) [   ] An employee benefit plan or endowment fund in accordance with

 (g) [   ] A parent holding company or control person in accordance with

 (h) [   ] A savings associations as defined in Section
           3(b) of the Federal Deposit Insurance Act;

 (i) [   ] A church plan that is excluded from the definition
           of an investment company under section 3(c)(14)
           of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

 (j) [   ] Group, in accordance with 240.13d-1(b)(1)(ii)(J).

Item 4. Ownership.

 (a) Amount beneficially owned:                         3,177,614

 (b) Percent of class:                                  7.35%

 (c) Number of shares as to which the person has:       3,177,614

Item 5. Ownership of Five Percent or Less of a Class

If this statement is being filed to report the fact
that as of the date hereof the reporting person has
ceased to be the beneficial owner of more than five
percent of the class of securities,
check the following [  ].

Instruction: Dissolution of a group requires a response to this item.

Item 6. Ownership of More than Five Percent on Behalf of Another Person.

Fiduciary Management, Inc. is an Investment Adviser registered under
the Investment Advisers Act of 1940. Its Principal Business is to
provide investment advisory services to institutions and individuals.
The shares to which this statement relates are owned directly by
various accounts managed by Fiduciary Management, Inc.
Such accounts have the right to receive dividends from,
and the proceeds from the sale of, the shares.

Item 7. Identification and Classification of the Subsidiary Which
        Acquired the Security Being Reported on By the Parent
        Holding Company or Control Person.

Item 8. Identification and Classification of Members of the Group

Item 9. Notice of Dissolution of Group

Item 10. Certification


After reasonable inquiry and to the best of my knowledge and belief,
I certify that the information set forth in this statement
is true, complete and correct.

                Date:   February 12, 2021

                        Jessica P. Taske
                        Vice President
                        Fiduciary Management, Inc.

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