wrist ball with massage and lights * Durable PC case and metal ball core * Silicon strap * Customer ... over 12,000 RPM.Function:1.Perfect exercise gadget for sports like golf, tennis, squash, cricket, badminton, ... , hands, forearms, biceps, triceps, ligament and shoulders3. Great benefit and avoid the ligament injuries who are the typists ... easy to be broken Wrist Ball with massage and lights- WB286L