SEC Filing Html Data



SCHEDULE 13G

Amendment No. 3
CompX International Incorporated
Class A Common Stock
Cusip # 20563P101


Cusip # 20563P101
Item 1:	Reporting Person - FMR Corp.
Item 4:	Commonwealth of Massachusetts
Item 5:	217,700
Item 6:	0
Item 7:	785,266
Item 8:	0
Item 9:	785,266
Item 11:	12.77%
Item 12:	    HC


Cusip # 20563P101
Item 1:	Reporting Person - Edward C. Johnson 3d
Item 4:	United States of America
Item 5:	0
Item 6:	0
Item 7:	785,266
Item 8:	0
Item 9:	785,266
Item 11:	12.77%
Item 12:	IN


Cusip # 20563P101
Item 1:	Reporting Person - Abigail P. Johnson
Item 4:	United States of America
Item 5:	None
Item 6:	None
Item 7:	785,266
Item 8:	None
Item 9:	785,266
Item 11:	12.77%
Item 12:	    IN



SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)


Item 1(a).	Name of Issuer:

		CompX International Incorporated

Item 1(b).	Name of Issuer's Principal Executive Offices:

		200 Old Mill Road
		Mauldin, SC 29662

Item 2(a).	Name of Person Filing:

		FMR Corp.

Item 2(b).	Address or Principal Business Office or, if None,
Residence:

		82 Devonshire Street, Boston, Massachusetts  02109

Item 2(c).	Citizenship:

		Not applicable

Item 2(d).	Title of Class of Securities:

		Class A Common Stock

Item 2(e).	CUSIP Number:

		20563P101

Item 3.	This statement is filed pursuant to Rule 13d-1(b) or 13d-
2(b) and the person filing, FMR Corp., is a parent
holding company in accordance with Section 240.13d-
1(b)(ii)(G).  (Note:  See Item 7).

Item 4.	Ownership

	(a)	Amount Beneficially Owned:
	785,266

	(b)	Percent of Class:
	12.77%

	(c)	Number of shares as to which such person has:

	(i)	sole power to vote or to direct the vote:
	217,700

	(ii)	shared power to vote or to direct the vote:
	0

	(iii)	sole power to dispose or to direct the
disposition of:	785,266

	(iv)	shared power to dispose or to direct the
disposition of:	0




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

	Not applicable.

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

	Various persons have the right to receive or the
power to direct the receipt of dividends from, or
the proceeds from the sale of, the Class A Common
Stock of CompX International Incorporated.  No one
person's interest in the Class A Common Stock of
CompX International Incorporated is more than five
percent of the total outstanding Class A Common
Stock.

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

	See attached Exhibit(s) A, B.

Item 8.	Identification and Classification of Members of the
Group.

	Not Applicable. See attached Exhibit A.

Item 9.	Notice of Dissolution of Group.

	Not applicable.

Item 10.	Certification.

	By signing below I certify that, to the best of my
knowledge and belief, the securities referred to
above were acquired in the ordinary course of
business and were not acquired for the purpose of
and do not have the effect of changing or
influencing the control of the issuer of such
securities and were not acquired in connection with
or as a participant in any transaction having such
purpose or effect.


Signature

	After reasonable inquiry and to the best of my
knowledge and belief, I certify that the information
set forth in this Schedule 13G in connection with
FMR Corp.'s beneficial ownership of the Class A
Common Stock of CompX International Incorporated at
December 31, 1999 is true, complete and correct.

	February 14, 2000
Date


	/s/Eric D. Roiter
Signature


	Eric D. Roiter
	Duly authorized under
Power of Attorney
	dated December 30, 1997,
by and on behalf
	of FMR Corp. and its
direct and indirect
	subsidiaries



SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)

	Pursuant to the instructions in Item 7 of Schedule 13G,
Fidelity Management & Research Company ("Fidelity"), 82
Devonshire Street, Boston, Massachusetts 02109, a wholly-owned
subsidiary of FMR Corp. and an investment adviser registered
under Section 203 of the Investment Advisers Act of 1940, is the
beneficial owner of 567,566 shares or 9.23% of the Class A Common
Stock outstanding of CompX International Incorporated  ("the
Company") as a result of acting as investment adviser to various
investment companies registered under Section 8 of the Investment
Company Act of 1940.

	Edward C. Johnson 3d, FMR Corp., through its control of
Fidelity, and the funds each has sole power to dispose of the
567,566 shares owned by the Funds.

	Neither FMR Corp. nor Edward C. Johnson 3d, Chairman of FMR
Corp., has the sole power to vote or direct the voting of the
shares owned directly by the Fidelity Funds, which power resides
with the Funds' Boards of Trustees.  Fidelity carries out the
voting of the shares under written guidelines established by the
Funds' Boards of Trustees.

	Fidelity Management Trust Company, 82 Devonshire Street,
Boston, Massachusetts 02109, a wholly-owned subsidiary of FMR
Corp. and a bank as defined in Section 3(a)(6) of the Securities
Exchange Act of 1934, is the beneficial owner of 217,700 shares
or 3.54% of the Class A Common Stock outstanding of the Company
as a result of its serving as investment manager of the
institutional account(s).

	Edward C. Johnson 3d and FMR Corp., through its control of
Fidelity Management Trust Company, each has sole dispositive
power over 217,700 shares and sole power to vote or to direct the
voting of 217,700 shares of Class A Common Stock owned by the
institutional account(s) as reported above.

	Strategic Advisers, Inc., 82 Devonshire Street, Boston, MA
02109, a wholly-owned subsidiary of FMR Corp. and an investment
adviser registered under Section 203 of the Investment Advisers
Act of 1940, provides investment advisory services to
individuals. It does not have sole power to vote or direct the
voting of shares of certain securities held for clients and has
sole dispositive power over such securities. As such, FMR Corp.'s
beneficial ownership may include shares beneficially owned
through Strategic Advisers, Inc.

	Members of the Edward C. Johnson 3d family are the
predominant owners of Class B shares of common stock of FMR
Corp., representing approximately 49% of the voting power of FMR
Corp.  Mr. Johnson 3d owns 12.0% and Abigail Johnson owns 24.5%
of the aggregate outstanding voting stock of FMR Corp.  Mr.
Johnson 3d is Chairman of FMR Corp. and Abigail P. Johnson is a
Director of FMR Corp.  The Johnson family group and all other
Class B shareholders have entered into a shareholders' voting
agreement under which all Class B shares will be voted in
accordance with the majority vote of Class B shares.
Accordingly, through their ownership of voting common stock and
the execution of the shareholders' voting agreement, members of
the Johnson family may be deemed, under the Investment Company
Act of 1940, to form a controlling group with respect to FMR
Corp.


 .



SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)
RULE 13d-1(f)(1)  AGREEMENT

	The undersigned persons, on February 14, 2000, agree and
consent to the joint filing on their behalf of this Schedule 13G
in connection with their beneficial ownership of the Class A
Common Stock of CompX International Incorporated at December 31,
1999.

FMR Corp.

By   /s/Eric D. Roiter
	Eric D. Roiter
	Duly authorized under Power of
Attorney
	dated December 30, 1997, by and on
behalf
	of FMR Corp. and its direct and
indirect
	subsidiaries

Edward C. Johnson 3d

By   /s/Eric D. Roiter
	Eric D. Roiter
	Duly authorized under Power of
Attorney
	dated December 30, 1997, by and on
behalf
	of Edward C. Johnson 3d

Abigail P. Johnson

By   /s/Eric D. Roiter
	Eric D. Roiter
	Duly authorized under Power of
Attorney
	dated December 30, 1997, by and on
behalf
	of Abigail P. Johnson

Fidelity Management & Research
Company

By   /s/Eric D. Roiter
	Eric D. Roiter
	Senior V.P. and General Counsel