Offers graded resistance and prehension for both single-hand and bilateral activities. 36 springs deliver measured resistance up to 21 lbs. (9.5kg). Four different knob styles allow grading of prehension throughout the range of resistance. Different surface textures on knobs aid in decreasing hypersensitivity. 16" x 16" on 5½" legs (41 x 41 x 14cm). Heavy-duty aluminum. Assembly required.