Filament bends when peak force threshold is reached. Test sensory levels and obtain objective data on the status of diminishing or return insensibility. Handle opens to a 90° angle. Finger indentations on handle provide a firm, comfortable hold. Color code shows pressure level. Each set comes in protective case with instructions included. 5 piece, hand: 2.83, 3.61, 4.31, 4.56, and 6.65.