This is an original WWII M2 switchblade. These were concealed within the center pocket of the M42 jump jacket, allowing tangled paratroopers to cut themselves free of their parachutes. It retains the desirable lanyard loop, which prevented the paratrooper from dropping the knife if suspended from an elevated surface. This example is the later version, with the black-painted metal grips. It was manufactured by Geo. Schrade in Bridgeport, Connecticut under the "Presto" product line. Unfortunately, the spring mechanism has seized up, requiring the manual lifting of the blade.