Featuring a 7-inch (18 cm) blade and issued with a sheath designed to double as a wire cutter, the M9 bayonet is designed to function not only as a combat knife but also as a multi-tool, capable of serving as a wire cutter, metal slicer, bottle opener, and screwdriver.

[1] Qual-A-Tec's M9 bayonet design won over 49 other competitors, and was the only contract bid entry to have a zero percent failure rate.

Finn's designs proved extremely popular, and were widely counterfeited and sold illegally by other makers.

[6] In 1989, Finn received U.S. patent 4,821,356, but unlicensed copies from Asia and Mexico cut into his legitimate sales.

After the Phrobis III bayonet contract was completed in 1989, rights to the M9 reverted to the United States Army and there were many subsequent versions from other companies.

LanCay received its first contract in March 1992, taking over production from Buck, for 30,000 knives, later increased to 50,000, with General Cutlery as a subcontractor.