Wrist Power Ball Wrist Strengthener and Forearm Exerciser for Stronger Arm Fingers Wrist BonesGOOD FOR HEALTHEfficiently 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. EASY TO USECompare with the old version need to start with string,our upgraded version is auto start design which is simple to start by rotating