... inertia like a gyroscope. It is powered by rotating the wrist. The faster we rotate the ball, the stronger the dynamic and torsion ... 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 ...