... inside the device.It is application by centrifugal force & inertia like a gyroscope. It is powered by rotating the wrist. The speed ... like golf, tennis, squash, cricket, badminton, baseball, bowling, basket-ball,, motocross, mountain climbing.2. Increases strength in fingers, wrists, hands ... The balance of the rotor has been corrected by computer, so the ball has very excellent stability.2) There is a ...