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I hope this helps:   Design and features

Designed for rapid production using a minimum of strategic metals and machine processes, the M3 trench knife used a relatively narrow 6.75-inch bayonet-style spear-point blade with a sharpened 3.5-inch secondary edge.[7][8][4][9][10][5] The blade was made of carbon steel, and was either blued or parkerized.[2][5] Production of the grooved leather handle was later simplified by forming the grip of stacked leather washers that were shaped by turning on a lathe, then polished and lacquered.[11][2] The steel crossguard had an angular bend at one end to facilitate a thumb rest.[2]

The M3 was initially issued with a riveted leather (M6) sheath with a protective guard designed to prevent the point from piercing the sheath and injuring the wearer.[5] A rawhide thong on the end of the sheath allowed the user to tie the sheathed knife to his leg.[5] The M6 was later dropped in favor of an OD fiber-type scabbard with steel throat (M8, M8A1).[2][12][5] U.S. paratroopers frequently wore an M3 and sheath tied to a boot for emergency use in cutting parachute lines or close-quarters defense.