This bayonet was designed to fit the US M1 Carbine and was mainly used during WWII and the Korean conflict. It is very similar to the US M3 Combat/Trench Knife.

The earliest M-4 bayonets were equipped with brown leather grips; later variants were equipped with black plastic grips.
This bayonet is detached from the carbine muzzle by simultaneously pressing - with thumb and finger - two pincer-like spring-loaded attaching locks on the pommel of the hilt.
Blade is unmarked, but underneath the cross-guard can be found the model designation US M4 and the maker (Aerial [ACC], Camillus, Case, Imperial, Kiffe [Japan], Kinfolks [KI], Pal, or Utica; there may be others yet to be identified). All metal parts are usually Parkerized dark gray or blued (early).

There are at least two scabbard variations. The most common are olive-drab (green) fiberglass body with steel throat (stamped with US M8 or US M8A1 over the maker). The US M8 stamped scabbard is the original type and does not have a metal drag; the US M8A1 stamped variant is later and has a metal drag.