Wrist Trainer Ball, Hand Strengthener Gyro Ball Wrist Exerciser, Efficiently rehabilitates wrist pain, humerus fracture, scaphoid fracture, radial head fracture, numbness in fingers, numb hands, fractured wrist, elbow tendonitis, broken bones, olecranon bursitis. Increases strength in fingers, wrists, hands, forearms, biceps, triceps, ligament and shoulders.