CompX International : 2024 Proxy Statement

TABLE OF CONTENTS

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GLOSSARY OF TERMS

"Alliance Advisors" means Alliance Advisors, LLC, our proxy management advisor who will act as inspector of election for the annual meeting of stockholders.

"401(k) Plan" means The Employee 401(k) Retirement Plan, a defined contribution plan.

"brokerage firm or other nominee" means a brokerage firm or other nominee such as a banking institution, custodian, trustee or fiduciary (other than our transfer agent, Computershare) through which a stockholder holds its shares of our common stock.

"broker/nominee non-vote" means a non-vote by a brokerage firm or other nominee for shares held for a client's account for which the brokerage firm or other nominee does not have discretionary authority to vote on a particular matter and has not received instructions from the client.

"Code" means the Internal Revenue Code of 1986, as amended.

"Computershare" means Computershare Trust Company, N.A., our stock transfer agent and registrar. "CompX," "us," "we" or "our" means CompX International Inc.

"Contran" means Contran Corporation, the parent corporation of our consolidated tax group. "Dixie Rice" means Dixie Rice Agricultural L.L.C., one of our parent companies.

"EWI" means EWI RE, Inc., a wholly owned subsidiary of NL that, prior to NL's sale of EWI's insurance and risk management business to a third party in November 2019, was a reinsurance brokerage and risk management company.

"Family Trust" means the Harold C. Simmons Family Trust No. 2, which was established for the benefit of Lisa K. Simmons and her late sister and their children.

"independent directors" means the following directors: Thomas E. Barry, Terri L. Herrington, Ann Manix, Gina A. Norris, Mary A. Tidlund and Kevin B. Kramer (who was a member of our board of directors until October 2023), as applicable.

"ISA" means an intercorporate services agreement between Contran and a related company pursuant to which employees of Contran provide certain services, including executive officer services, to such related company on an annual fixed fee basis.

"Kronos Worldwide" means Kronos Worldwide, Inc., one of our publicly held sister corporations that is an international manufacturer of titanium dioxide products.

"named executive officer" means any person named in the 2023 Summary Compensation Table in this proxy statement.

"NL" means NL Industries, Inc., one of our publicly held parent corporations that is a diversified holding company (i) of which we are a subsidiary and (ii) that holds a significant investment in Kronos Worldwide.

"NLKW" means NLKW Holding, LLC, a wholly owned subsidiary of NL, which holds a significant equity interest in Kronos Worldwide.

"NYSE American" means the NYSE American (formerly named NYSE MKT), the stock exchange on which our shares of class A common stock trade.

"PCAOB" means the Public Company Accounting Oversight Board, a private sector, non-profit corporation that oversees auditors of U.S. public companies.

"PwC" means PricewaterhouseCoopers LLP, our independent registered public accounting firm.

"record date" means the close of business on March 26, 2024, the date our board of directors set for the determination of stockholders entitled to notice of and to vote at the 2024 annual meeting of our stockholders.

"RPT Policy" means the CompX International Inc. Policy Regarding Related Party Transactions, as amended and restated effective March 2, 2022.

"Say-on-Pay" means the second proposal in this proxy statement for a nonbinding advisory vote for the consideration of our stockholders to approve the compensation of our named executive officers as such proposal is described and as such compensation is disclosed in this proxy statement.

"SEC" means the U.S. Securities and Exchange Commission.

"Securities Exchange Act" means the Securities Exchange Act of 1934, as amended.

"stockholder of record" means a stockholder of our class A common stock who holds shares in its name in certificate form or electronically with our transfer agent, Computershare.

"Tall Pines" means Tall Pines Insurance Company, an indirect wholly owned captive insurance subsidiary of Valhi.

"Valhi" means Valhi, Inc., one of our publicly held parent corporations that is a diversified holding company of which NL and Kronos Worldwide are subsidiaries.

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1. Who is allowed to vote at the annual meeting?

1. The board of directors has set the close of business on March 26, 2024 as the record date for the determination of stockholders entitled to notice of and to vote at the meeting. Only holders of our class A common stock as of the close of business on the record date are entitled to vote at the meeting. On the record date, 12,313,757 shares of our class A common stock were issued and outstanding. Each share of our class A common stock entitles its holder to one vote.

1. How do I vote if I am a stockholder of record?

1. If you hold shares of our class A common stock in your name in certificate form or electronically with our transfer agent, Computershare, and not through a brokerage firm or other nominee, you are a stockholder of record. As a stockholder of record, you may:
2. • vote over the internet at www.AALvote.com/CIX;
   • vote by telephone using the voting procedures set forth on your proxy card;
   • instruct the agents named on your proxy card how to vote your shares by completing, signing and mailing the enclosed proxy card in the envelope provided; or
   • vote in person at the annual meeting.

1. What are the consequences if I am a stockholder of record and I execute my proxy card but do not indicate how I would like my shares voted for one or more of the director nominees named in this proxy statement or proposal 2 (Say-on-Pay)?

1. If you are a stockholder of record, the agents named on your proxy card will vote your shares on such uninstructed nominee or proposal as recommended by the board of directors in this proxy statement.

1. How do I vote if my shares are held through a brokerage firm or other nominee?

1. If you hold your shares through a brokerage firm or other nominee, you must follow the instructions on your voting instruction form on how to vote your shares. In order to ensure your brokerage firm or other nominee votes your shares in the manner you would like, you must provide voting instructions to your brokerage firm or other nominee by the deadline provided on your voting instruction form.
   Brokerage firms or other nominees may not vote your shares on the election of a director nominee or proposal 2 in the absence of your specific instructions as to how to vote. We encourage you to provide instructions to your brokerage firm or other nominee regarding the voting of your shares. If you do not instruct your brokerage firm or other nominee how to vote with respect to the election of a director nominee or proposal 2, your brokerage firm or other nominee may not vote with respect to the election of such director nominee or on proposal 2 and your vote will be counted as a "broker/nominee non-vote." "Broker/nominee non-votes"are non-votesby a brokerage firm or other nominee for shares held in a client's account for which the brokerage firm or other nominee does not have discretionary authority to vote on a particular matter and has not received instructions from the client. How we treat broker/nominee non-votesis separately described in each of the answers below regarding what constitutes a quorum and the requisite votes necessary to elect a director nominee or approve proposal 2.

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1. If I hold my shares through a brokerage firm or other nominee, how may I vote in person at the annual meeting?

1. If you wish to vote in person at the annual meeting, you will need to follow the instructions on your voting instruction form on how to obtain the appropriate documents to vote in person at the meeting.

1. Who will count the votes?

1. The board of directors has appointed Alliance Advisors to ascertain the number of shares represented, tabulate the vote and serve as inspector of election for the meeting.

1. Is my vote confidential?

1. Yes. All proxy cards, ballots or voting instructions will be kept confidential in accordance with our bylaws.

1. How do I change or revoke my proxy instructions if I am a stockholder of record?

1. If you are a stockholder of record, you may change or revoke your proxy instructions in any of the following ways:
2. • delivering to Alliance Advisors a written revocation;
   • submitting another proxy card bearing a later date;
   • changing your vote on www.AALvote.com/CIX;
   • using the telephone voting procedures set forth on your proxy card; or
   • voting in person at the annual meeting.

1. How do I change or revoke my voting instructions if my shares are held through a brokerage firm or other nominee?

1. If your shares are held through a brokerage firm or other nominee, you must follow the instructions from your brokerage firm or other nominee on how to change or revoke your voting instructions or how to vote in person at the annual meeting.

1. What constitutes a quorum?

1. A quorum is the presence, in person or by proxy, of the holders of a majority of the votes from holders of the outstanding shares of our class A common stock entitled to vote at the meeting.
   Shares that are voted "abstain" or "withheld" are counted as present and entitled to vote and are, therefore, included for purposes of determining whether a quorum is present at the annual meeting.
   As already discussed in the previous answer regarding how to vote shares held through a brokerage firm or other nominee, there are no proposals for the annual meeting that would allow a brokerage firm or nominee to cast a vote on uninstructed shares. If a brokerage firm or other nominee receives no instruction for the election of any director nominee and receives no instruction for proposal 2, such uninstructed shares will be counted as not entitled to cast a vote and are, therefore, not considered for purposes of determining whether a quorum is present at the annual meeting. If a brokerage firm or other nominee receives instructions on the election of at least one director nominee or on proposal 2, such instructed shares will be counted as present and entitled to cast a vote and are, therefore, included for purposes of determining whether a quorum is present at the annual meeting.
   NL directly held approximately 87.3% of the outstanding shares of our class A common stock as of the record date. NL has indicated its intention to have its shares of our common stock represented at the meeting. If NL attends the meeting in person or by proxy, the meeting will have a quorum present.

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1. Assuming a quorum is present, what vote is required to elect a director nominee?

1. Under applicable state law and our governing documents, a plurality of affirmative votes of the holders of our outstanding shares of common stock represented and entitled to vote at the meeting is necessary to elect each director nominee. Our governing documents do not authorize cumulative voting. Accordingly, the eight candidates receiving the highest number of affirmative votes at the annual meeting will be elected as directors. Only shares that are voted in favor of a particular nominee will be counted toward that nominee's achievement of a plurality. There is no "against" option, and votes that are "withheld" or not cast, including broker/nominee non-votes, will not be counted toward that nominee's achievement of a plurality.
   NL has indicated its intention to have its shares of our common stock represented at the meeting and to vote such shares FOR the election of each of the director nominees named in this proxy statement. If NL attends the meeting in person or by proxy and votes as indicated, the stockholders will elect all of the nominees named in this proxy statement to the board of directors.

1. Assuming a quorum is present, what vote is required to adopt and approve proposal 2 (Say-on-Pay)?

1. The stockholder resolution contained in this proposal provides that the nonbinding affirmative vote of the holders of the majority of the outstanding shares of our class A common stock present in person or represented by proxy at the meeting and entitled to vote on the subject matter will be the requisite vote to adopt the resolution and approve the compensation of our named executive officers as such compensation is disclosed in this proxy statement. Abstentions will be counted as represented and entitled to vote and will therefore have the effect of a negative vote. Broker/nominee non-votes will not be counted as entitled to vote and will have no effect on this proposal.
   NL has indicated its intention to have its shares of our common stock represented at the meeting and to vote such shares FOR this nonbinding advisory proposal. If NL attends the meeting in person or by proxy and votes as indicated, the stockholders will, by a nonbinding advisory vote, approve this proposal.

1. Assuming a quorum is present, what vote is required to approve any other matter to come before the meeting?

1. Except as applicable laws may otherwise provide, the approval of any other matter that may properly come before the meeting will require the affirmative vote of the holders of the majority of the class A common stock present in person or represented by proxy at the annual meeting and entitled to vote on the subject matter. Abstentions will be counted as represented and entitled to vote and will therefore have the effect of a negative vote.

1. If I am a stockholder of record, how will the agents named on my proxy card vote on any other matter to come before the meeting?

1. If you are a stockholder of record and to the extent allowed by applicable law, the agents named on your proxy card will vote in their discretion on any other matter that may properly come before the meeting.

1. Who will pay for the cost of soliciting the proxies?

1. We will pay all expenses related to the solicitation, including charges for preparing, printing, assembling and distributing all materials delivered to stockholders. In addition to the solicitation by mail, our directors, officers and regular employees may solicit proxies by telephone or in person for which such persons will receive no additional compensation. Upon request, we will reimburse brokerage firms or other nominees for their reasonable out-of-pocket expenses incurred in distributing proxy materials and voting instruction forms to the beneficial owners of our class A common stock that hold such stock in accounts with such entities.

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CONTROLLING STOCKHOLDER

NL directly held approximately 87.3% of the outstanding shares of our class A common stock as of the record date. NL has indicated its intention to have its shares of our common stock represented at the meeting and to vote such shares FOR the election of each of the director nominees named in this proxy statement and FOR proposal 2 (Say-on- Pay). If NL attends the meeting in person or by proxy and votes as indicated, the meeting will have a quorum present and the stockholders will elect all of the nominees named in this proxy statement to the board of directors and approve proposal 2.

SECURITY OWNERSHIP

Ownership of CompX. The following table and footnotes set forth as of the record date the beneficial ownership, as defined by regulations of the SEC, of our class A common stock held by each individual, entity or group known to us to own beneficially more than 5% of the outstanding shares of our class A common stock, each of our directors, each of the named executive officers, and all of our current directors and executive officers as a group. See footnotes 3 and 4 below for information concerning the relationships of certain individuals and entities that may be deemed to own indirectly and beneficially more than 5% of the outstanding shares of our class A common stock. All information is taken from or based upon ownership filings made by such individuals or entities with the SEC or upon information provided by such individuals or entities.

• Less than 1%.

1. Beneficial ownership as reported in the above table has been determined in accordance with Rule 13d-3 under the Securities Exchange Act, and is not necessarily indicative of beneficial ownership for any other purpose. Except as otherwise noted, the listed entities, individuals or group have sole investment power and sole voting power as to all shares set forth opposite their names. Except as noted in footnote 4 to this table, the business address for each listed person or entity is Three Lincoln Centre, 5430 LBJ Freeway, Suite 1700, Dallas, Texas 75240-2620.
2. The percentages set forth above and in the following footnotes are based on 12,313,757 shares of our class A common stock outstanding as of the record date.

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