The M9 Bayonet is a multi-purpose knife and bayonet officially adopted in 1984 by the U.S. Army. It has a 7-inch blade and is issued with a sheath designed to double as a wire cutter.
The M9 Bayonet partially replaced the older M7 Bayonet, introduced in 1964.
The M6 bayonet-knife was used as a bayonet on the M14 series rifle and as a hand weapon. The M7 bayonet-knife was used as a bayonet on the M16 series rifle, the M4 carbine and as a hand weapon. The M9 multi-purpose bayonet system is used as a bayonet on the M16 series rifle, on the M4 series carbine, as a hand weapon, as a general field and utility knife as well as a wire cutter together with its scabbard, and as a saw.