Additional Information

NL, Industries, Inc. ("NL"), Valhi, Inc. ("Valhi") and Tremont LLC
("Tremont") are the holders of 51.2%, 32.0% and 10.4%, respectively, of
the outstanding shares of common stock, par value $0.01 per share
("Common Stock"), of the issuer.

Valhi and Tremont are the direct holders of approximately 62.6% and
21.2%, respectively, of the outstanding common stock of NL.  Valhi is
the direct holder of 100% of the membership interests of Tremont.
Valhi Group, Inc. ("VGI"), National City Lines, Inc. ("National"),
Contran, the Harold Simmons Foundation, Inc. (the "Foundation"), the
Contran Deferred Compensation Trust No. 2 (the "CDCT No. 2") and The
Combined Master Retirement Trust (the "CMRT") are the direct holders of
approximately 77.6%, 9.1%, 3.1%, 0.9%, 0.4% and 0.1%, respectively, of
the outstanding shares of Valhi common stock.  National, NOA, Inc.
("NOA") and Dixie Holding Company ("Dixie Holding") are the direct
holders of approximately 73.3%, 11.4% and 15.3%, respectively, of the
outstanding common stock of VGI.  Contran and NOA are the direct
holders of approximately 85.7% and 14.3%, respectively, of the
outstanding common stock of National.  Contran and Southwest Louisiana
Land Company, Inc.  ("Southwest") are the direct holders of
approximately 48.9% and 51.1%, respectively, of the outstanding common
stock of NOA.  Dixie Rice Agricultural Corporation, Inc. ("Dixie Rice")
is the direct holder of 100% of the outstanding common stock of Dixie
Holding.  Contran is the holder of 100% of the outstanding common stock
of Dixie Rice and approximately 88.9% of the outstanding common stock
of Southwest.

Substantially all of Contran's outstanding voting stock is held by
trusts established for the benefit of certain children and
grandchildren of Harold C. Simmons (the "Trusts"), of which Mr. Simmons
is the sole trustee.  As sole trustee of each of the Trusts, Mr.
Simmons has the power to vote and direct the disposition of the shares
of Contran stock held by each of the Trusts.

Harold C. Simmons is the chairman of the board and chief executive
officer of each of the issuer and NL and the chairman of the board of
each of Tremont, Valhi, VGI, National, NOA, Dixie Holding, Dixie Rice,
Southwest and Contran.

The Foundation directly holds approximately 0.9% of the outstanding
shares of Valhi common stock.  The Foundation is a tax-exempt
foundation organized for charitable purposes.  Harold C. Simmons is the
chairman of the board of the Foundation.

The CDCT No. 2 directly holds approximately 0.4% of the outstanding
shares of Valhi common stock.  U.S. Bank National Association serves as
the trustee of the CDCT No. 2.  Contran established the CDCT No. 2 as
an irrevocable "rabbi trust" to assist Contran in meeting certain
deferred compensation obligations that it owes to Harold C. Simmons.
If the CDCT No. 2 assets are insufficient to satisfy such obligations,
Contran is obligated to satisfy the balance of such obligations as they
come due.  Pursuant to the terms of the CDCT No. 2, Contran (i) retains
the power to vote the shares of Valhi common stock held directly by the
CDCT No. 2, (ii) retains dispositive power over such shares and (iii)
may be deemed the indirect beneficial owner of such shares.

The CMRT directly holds approximately 0.1% of the outstanding shares of
Valhi common stock.  Valhi established the CMRT to permit the
collective investment by master trusts that maintain the assets of
certain employee benefit plans Valhi and related companies adopt.
Harold C. Simmons is the sole trustee of the CMRT and a member of the
trust investment committee for the CMRT.  Valhi's board of directors
selects the trustee and members of the trust investment committee for
the CMRT.  Harold C. Simmons disclaims beneficial ownership of the
shares of Valhi common stock held by the CMRT, except to the extent of
his individual vested beneficial interest, if any, in the assets held
by the CMRT.

By virtue of the holding of the offices, the stock ownership and his
services as trustee, all as described above, (a) Harold C. Simmons may
be deemed to control such entities and (b) Mr. Simmons and certain of
such entities may be deemed to possess indirect beneficial ownership of
shares directly held by certain of such other entities.  However, Mr.
Simmons disclaims such beneficial ownership of the shares beneficially
owned directly or indirectly by any of such entities, except to the
extent of his vested beneficial interest, if any, in shares held by the
CMRT and his interest as a beneficiary of the CDCT No. 2.  Mr. Harold
Simmons disclaims beneficial ownership of all shares of Common Stock
that NL, Valhi or Tremont directly holds.

Harold C. Simmons' spouse is the direct owner of 34,737 shares of
Common Stock and 69,475 shares of NL common stock.  Mr. Simmons may be
deemed to share indirect beneficial ownership of such shares.  Mr.
Simmons disclaims all such beneficial ownership.

Harold C. Simmons directly holds 3,000 shares of Common Stock, 14,000
shares of NL common stock (including stock options exercisable for
8,000 shares) and 3,383 shares of Valhi common stock.

Valmont Insurance Company ("Valmont"), NL and a subsidiary of NL
directly own 1,000,000, 3,522,967 and 1,186,200 shares of Valhi common
stock, respectively. Valhi is the direct holder of 100% of the
outstanding common stock of Valmont.  Pursuant to Delaware law, Valhi
treats the shares of Valhi common stock that Valmont, NL, and the
subsidiary of NL own as treasury stock for voting purposes.  For the
purposes of the percentage calculations herein, such shares are not
deemed outstanding.