... : 350g 3. 30pcs/ctn Hotsale! LED Energy Wrist Ball With Speedometer Sport Toy Red There is no any battery or electricity inside ... powered by rotating the wrist. The faster we rotate the ball, the stronger the dynamic and torsion is produced. The ... like golf, tennis, squash, cricket, badminton, baseball, bowling, basket-ball,, motocross, mountain climbing.2. Increases strength in fingers, wrists, hands ...