1.durable plastic with steel axle 2.no any battery, powered by rotating the wrist 3.Great quality 4. Paypal supported It is a application by centrifugal force & inertia like a gyroscapeMaterial: durable plastic with steel axle Function:1.Perfect exercise gadget for sports like golf, tennis, squash, cricket, badminton, baseball, bowling,basketball, motocross, mountain climbing.2.Increases strength ...