| 1 | NAMES OF REPORTING PERSONS NL Industries, Inc. | ||
| 2 | CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a)  □ (b)  □ | ||
| 3 | SEC USE ONLY | ||
| 4 | SOURCE OF FUNDS (SEE INSTRUCTIONS) | ||
| 5 | CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  □ | ||
| 6 | CITIZENSHIP OR PLACE OF ORGANIZATION New Jersey | ||
| NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH | 7 | SOLE VOTING POWER              -0- | |
| 8 | SHARED VOTING POWER 10,758,104 | ||
| 9 | SOLE DISPOSITIVE POWER              -0- | ||
| 10 | SHARED DISPOSITIVE POWER 10,758,104 | ||
| 11 | AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 10,758,104 | ||
| 12 | CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)  □ | ||
| 13 | PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 86.5% | ||
| 14 | TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) CO | ||
| 1 | NAMES OF REPORTING PERSONS Kronos Worldwide, Inc. | ||
| 2 | CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a)  □ (b)  □ | ||
| 3 | SEC USE ONLY | ||
| 4 | SOURCE OF FUNDS (SEE INSTRUCTIONS) | ||
| 5 | CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  □ | ||
| 6 | CITIZENSHIP OR PLACE OF ORGANIZATION Delaware | ||
| NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH | 7 | SOLE VOTING POWER              -0- | |
| 8 | SHARED VOTING POWER 10,758,104 | ||
| 9 | SOLE DISPOSITIVE POWER              -0- | ||
| 10 | SHARED DISPOSITIVE POWER 10,758,104 | ||
| 11 | AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 10,758,104 | ||
| 12 | CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)  □ | ||
| 13 | PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 86.5% | ||
| 14 | TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) CO | ||
| 1 | NAMES OF REPORTING PERSONS Valhi, Inc. | ||
| 2 | CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a)  □ (b)  □ | ||
| 3 | SEC USE ONLY | ||
| 4 | SOURCE OF FUNDS (SEE INSTRUCTIONS) | ||
| 5 | CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  □ | ||
| 6 | CITIZENSHIP OR PLACE OF ORGANIZATION Delaware | ||
| NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH | 7 | SOLE VOTING POWER              -0- | |
| 8 | SHARED VOTING POWER 10,758,104 | ||
| 9 | SOLE DISPOSITIVE POWER              -0- | ||
| 10 | SHARED DISPOSITIVE POWER 10,758,104 | ||
| 11 | AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 10,758,104 | ||
| 12 | CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)  □ | ||
| 13 | PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 86.5% | ||
| 14 | TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) CO | ||
| 1 | NAMES OF REPORTING PERSONS Dixie Rice Agricultural L.L.C. | ||
| 2 | CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a)  □ (b)  □ | ||
| 3 | SEC USE ONLY | ||
| 4 | SOURCE OF FUNDS (SEE INSTRUCTIONS) | ||
| 5 | CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  □ | ||
| 6 | CITIZENSHIP OR PLACE OF ORGANIZATION Louisiana | ||
| NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH | 7 | SOLE VOTING POWER              -0- | |
| 8 | SHARED VOTING POWER 10,758,104 | ||
| 9 | SOLE DISPOSITIVE POWER              -0- | ||
| 10 | SHARED DISPOSITIVE POWER 10,758,104 | ||
| 11 | AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 10,758,104 | ||
| 12 | CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)  □ | ||
| 13 | PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 86.5% | ||
| 14 | TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) OO | ||
| 1 | NAMES OF REPORTING PERSONS Contran Corporation | ||
| 2 | CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a)  □ (b)  □ | ||
| 3 | SEC USE ONLY | ||
| 4 | SOURCE OF FUNDS (SEE INSTRUCTIONS) | ||
| 5 | CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  □ | ||
| 6 | CITIZENSHIP OR PLACE OF ORGANIZATION Delaware | ||
| NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH | 7 | SOLE VOTING POWER              -0- | |
| 8 | SHARED VOTING POWER 10,764,004 | ||
| 9 | SOLE DISPOSITIVE POWER              -0- | ||
| 10 | SHARED DISPOSITIVE POWER 10,764,004 | ||
| 11 | AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 10,764,004 | ||
| 12 | CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)  □ | ||
| 13 | PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 86.5% | ||
| 14 | TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) CO | ||
| 1 | NAMES OF REPORTING PERSONS Lisa K. Simmons | ||
| 2 | CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a)  □ (b)  □ | ||
| 3 | SEC USE ONLY | ||
| 4 | SOURCE OF FUNDS (SEE INSTRUCTIONS) | ||
| 5 | CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  □ | ||
| 6 | CITIZENSHIP OR PLACE OF ORGANIZATION USA | ||
| NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH | 7 | SOLE VOTING POWER              -0- | |
| 8 | SHARED VOTING POWER 10,764,004 | ||
| 9 | SOLE DISPOSITIVE POWER              -0- | ||
| 10 | SHARED DISPOSITIVE POWER 10,764,004 | ||
| 11 | AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON -0- | ||
| 12 | CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)  ý | ||
| 13 | PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.0% | ||
| 14 | TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) IN | ||
| 1 | NAMES OF REPORTING PERSONS Serena Simmons Connelly | ||
| 2 | CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a)  □ (b)  □ | ||
| 3 | SEC USE ONLY | ||
| 4 | SOURCE OF FUNDS (SEE INSTRUCTIONS) | ||
| 5 | CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  □ | ||
| 6 | CITIZENSHIP OR PLACE OF ORGANIZATION USA | ||
| NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH | 7 | SOLE VOTING POWER          2,000 | |
| 8 | SHARED VOTING POWER 10,764,004 | ||
| 9 | SOLE DISPOSITIVE POWER          2,000 | ||
| 10 | SHARED DISPOSITIVE POWER 10,764,004 | ||
| 11 | AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,000 | ||
| 12 | CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)  ý | ||
| 13 | PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.0% | ||
| 14 | TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) IN | ||
| 1 | NAMES OF REPORTING PERSONS Harold C. Simmons Family Trust No. 2 | ||
| 2 | CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a)  □ (b)  □ | ||
| 3 | SEC USE ONLY | ||
| 4 | SOURCE OF FUNDS (SEE INSTRUCTIONS) | ||
| 5 | CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)  □ | ||
| 6 | CITIZENSHIP OR PLACE OF ORGANIZATION Texas | ||
| NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH | 7 | SOLE VOTING POWER              -0- | |
| 8 | SHARED VOTING POWER 10,764,004 | ||
| 9 | SOLE DISPOSITIVE POWER              -0- | ||
| 10 | SHARED DISPOSITIVE POWER 10,764,004 | ||
| 11 | AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON -0- | ||
| 12 | CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)  ý | ||
| 13 | PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.0% | ||
| 14 | TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) OO | ||
| Item 2. | Identity and Background. | 
| • | NL Industries, Inc. (“NL”) as a direct holder of Class A Shares; | 
| • | Kronos Worldwide, Inc. (“Kronos Worldwide”), Valhi, Inc. (“Valhi”), Dixie Rice Agricultural L.L.C. (“Dixie Rice”) and Contran Corporation (“Contran”) by virtue of their direct or indirect ownership of NL; | 
| • | Lisa K. Simmons by virtue of ownership of outstanding voting stock of Contran by her and entities related to her, and her position as co-chair of the Contran board of directors (the “Contran Board”); | 
| • | Serena Simmons Connelly by virtue of ownership of outstanding voting stock of Contran by her and entities related to her, and her position as co-chair of the Contran Board; and | 
| • | the Harold C. Simmons Family Trust No. 2 (the “Family Trust”), by virtue of its ownership of outstanding voting stock of Contran. | 
| NL  | 86.4% | 
| Contran  | Less than 1% | 
| Kronos Worldwide  | Less than 1% | 
| Serena Simmons Connelly  | Less than 1% | 
| Valhi  | 82.8% | 
| Kronos Worldwide  | Less than 1% | 
| Serena Simmons Connelly  | Less than 1% | 
| Valhi  | 50.1% | 
| NLKW Holding LLC (“NLKW”)  | 30.4% | 
| Contran  | Less than 1% | 
| Serena Simmons Connelly  | Less than 1% | 
| Dixie Rice  | 91.5% | 
| Serena Simmons Connelly  | Less than 1% | 
| Item 4. | Purpose of Transaction. | 
| Item 5. | Interest in Securities of the Issuer. | 
| Reporting Persons | Class A Shares Directly Held | |||
| NL  | 10,755,104 | |||
| Contran  | 5,900 | |||
| Kronos Worldwide  | 3,000 | |||
| Serena Simmons Connelly  | 2,000 | |||
| Total  | 10,766,004 | |||
| Item 7. | Material to be Filed as Exhibits. | 
| Exhibit 1*  | Joint Filing Agreement dated as of September 4, 2019, among the Reporting Persons. | 
| By: | Tolleson Private Bank, not in its individual capacity but solely as trustee of the Harold C. Simmons Family Trust No. 2 | 
| By: | /s/ Tracey L. Reyes | 
| Name: | Tracey L. Reyes | 
| Title: | Vice President, Director of Private Trust | 
| Entity | Officer positions | 
| Contran Corporation | President and Chief Executive Officer | 
| Dixie Rice Agricultural L.L.C. | President and Chief Executive Officer | 
| Valhi, Inc. | Vice Chairman of the Board, President and Chief Executive Officer | 
| Kronos Worldwide, Inc. | Vice Chairman of the Board, President and Chief Executive Officer | 
| NL Industries, Inc. | Vice Chairman of the Board and Chief Executive Officer | 
| Name | Present Principal Occupation | 
| Thomas E. Barry  | Professor of marketing, emeritus at the Edwin L. Cox School of Business at Southern Methodist University; and a director of CompX and Valhi | 
| Patty S. Brinda  | Vice president and controller of NL | 
| James W. Brown  | Senior vice president and chief financial officer of Kronos Worldwide and Valhi | 
| Clarence B. Brown, III  | Vice president, general counsel and secretary of Kronos Worldwide; and vice president and secretary of NL | 
| James Buch  | Chief operating officer of Kronos Worldwide | 
| Brian W. Christian  | Executive vice president of Kronos Worldwide; and senior vice president of Contran | 
| Benjamin R. Corona  | President, global sales management of Kronos Worldwide | 
| Serena S. Connelly  | Co-chair of the board of Contran | 
| Steven S. Eaton  | Vice president, internal control over financial reporting of CompX, Kronos Worldwide, NL and Valhi | 
| Loretta J. Feehan  | Chair of the board (non-executive) of CompX, Kronos Worldwide, NL and Valhi; and certified public accountant who consults on financial and tax matters | 
| Robert D. Graham  | Vice chairman of the board of CompX; vice chairman of the board and chief executive officer of NL; vice chairman of the board, president and chief executive officer of Kronos Worldwide and
              Valhi; chairman of the board, president and chief executive officer of Dixie Rice; and director, president and chief executive officer of Contran | 
| Name | Present Principal Occupation | 
| Jane R. Grimm  | Vice president and secretary of CompX and Valhi | 
| Tim C. Hafer  | Senior vice president and controller of Kronos Worldwide | 
| Bryan A. Hanley  | Vice president and treasurer of CompX, NL, Kronos Worldwide, Valhi and Contran | 
| John E. Harper  | Private investor; and a director of Kronos Worldwide and NL | 
| Terri L. Herrington  | Private investor; and a director of CompX and Valhi | 
| Janet G. Keckeisen  | Vice president, corporate strategy and investor relations of Kronos Worldwide and Valhi | 
| Patricia A. Kropp  | Vice president, global human resources of Kronos Worldwide; vice president, employee benefits of NL; and vice president, human resources of Contran | 
| Kelly D. Luttmer  | Executive vice president and chief tax officer of CompX, Kronos Worldwide, NL, Valhi, Dixie Rice and Contran | 
| W. Hayden McIlroy (1)  | Private investor primarily in real estate; and a director of Valhi | 
| Meredith W. Mendes  | Executive director and chief operating officer of Jenner & Block LLP; and a director of Kronos Worldwide and NL | 
| Cecil H. Moore, Jr.  | Private investor; and a director of Kronos Worldwide and NL | 
| Andrew B. Nace  | Executive vice president of CompX, Kronos Worldwide and NL; executive vice president, general counsel and secretary of Valhi; and executive vice president, general counsel and secretary of
              Dixie Rice and Contran | 
| John R. Powers, III  | Vice president and general counsel of NL | 
| Name | Present Principal Occupation | 
| Courtney J. Riley  | Vice president, environmental affairs of Kronos Worldwide; president of NL; executive vice president, environmental affairs of Valhi; and senior vice president, environmental affairs of Contran | 
| Amy Allbach Samford  | Vice president and chief financial officer of CompX and NL; and vice president and controller of Valhi and Contran | 
| Michael S. Simmons  | Vice president, finance of Kronos Worldwide; and  vice president and chief accounting officer of Valhi | 
| Lisa K. Simmons  | Co-chair of the board of Contran | 
| Thomas P. Stafford  | Chairman of the NASA Advisory Council Task Force on the International Space Station Program; and a director of Kronos Worldwide and NL | 
| John A. Sunny  | Vice president and chief information officer of Kronos Worldwide; and vice president, information technology of Valhi and Contran | 
| Gregory M. Swalwell  | Executive vice president, chief financial officer and chief accounting officer of Dixie Rice and Contran | 
| Mary A. Tidlund (2)  | Private investor; and a director of CompX and Valhi | 
| R. Gerald Turner (3)  | President of Southern Methodist University; and a director of Kronos Worldwide | 
| (1) | The principal business address for Mr. McIlroy is 25 Highland Park Village, Suite 100-341, Dallas, Texas 75205. | 
| (2) | Ms. Tidlund is a citizen of Canada. | 
| (3) | The principal business address for Dr. Turner is Southern Methodist University, Perkins Administration Bldg. #225, 6425 Boaz Lane, Dallas, Texas 75275. | 
| Name | Class A Shares Held | |
| Thomas E. Barry  | 4,600 | |
| Clarence B. Brown, III  | -0- | |
| James W. Brown  | -0- | |
| James Buch  | -0- | |
| Brian W. Christian  | -0- | |
| Benjamin R. Corona  | -0- | |
| Serena S. Connelly  | 2,000 | (1) | 
| Steven S. Eaton  | -0- | |
| Loretta J. Feehan  | 6,600 | |
| Robert D. Graham  | 1,000 | |
| Tim C. Hafer  | -0- | |
| Bryan A. Hanley  | -0- | |
| John E. Harper  | -0- | |
| Terri L. Herrington  | 2,600 | |
| Janet G. Keckeisen  | -0- | |
| Patricia A. Kropp  | -0- | |
| Kelly D. Luttmer  | 200 | |
| Meredith W. Mendes  | -0- | |
| W. Hayden McIlroy  | -0- | |
| Name | Class A Shares Held | |
| Cecil H. Moore, Jr.  | 3,350 | |
| Andrew B. Nace  | -0- | |
| John R. Powers, III  | -0- | |
| Courtney J. Riley  | -0- | |
| Amy Allbach Samford  | -0- | |
| Lisa K. Simmons  | -0- | (2) | 
| Thomas P. Stafford  | -0- | |
| John A. Sunny  | -0- | |
| Gregory M. Swalwell  | -0- | |
| Mary A. Tidlund  | 4,600 | |
| R. Gerald Turner.  | -0- | |
| (1) | Does not include other Class A Shares of which Ms. Connelly may be deemed to possess indirect beneficial ownership as described in Items 2 and 5(a) of this Statement.  Except for the 2,000
                Class A Shares that she holds directly, Ms. Connelly disclaims beneficial ownership of all Shares. | 
| (2) | Does not include Class A Shares of which Ms. Simmons may be deemed to possess indirect beneficial ownership as described in Items 2 and 5(a) of this Statement.  Ms. Simmons disclaims
                beneficial ownership of all Shares. | 
| By: | Tolleson Private Bank, not in its individual capacity but solely as trustee of the Harold C. Simmons Family Trust No. 2 | 
| By: | /s/ Tracey L. Reyes | 
| Name: | Tracey L. Reyes | 
| Title: | Vice President, Director of Private Trust |