To evaluate the performance of the prehensors, subjects will complete a randomized A-B crossover study with a subjective follow-up. Two subject categories will be evaluated: 1.) healthy non-amputees, and 2.) unilateral transradial amputee subjects who currently use, or are interested in using a body-powered prosthesis. We anticipate data collection data with 10 non-amputee subject, and 8 amputee subjects.