Abstract: A human forearm prosthesis is disclosed which has attached thereto a device comprising a housing, a knife blade suitable for cutting food, a projection on the knife blade for restraining the travel of the knife blade into the housing when it is desired to retract the knife blade into the housing for storage thereof, and out of the housing when it is desired to extend the knife blade for use of the knife blade for cutting food. Preferably, the knife blade moves into and out of the housing by force of gravity. The travel of the knife blade is restrained by a guide slot which extends substantially the length of the housing and a projection located on or near the back end of the knife blade, which projection travels in the guide slot. The device of the invention has a spring operated knife blade release mechanism that blocks the knife blade from passing out of the housing when it is desired to restrain the blade in retracted position.