... ball with NEON&counter Increase strength of fingers,wrists,hands,forearms, biceps,triceps OEM There is no any battery or ... reach over 12,000 RPM.TheoryLike gyroscopes.centrifugal force and inertia are applied.Function:1.Perfect exercise gadget for ... fingers, wrists, hands, forearms, biceps, triceps, ligament and shoulders3. Great benefit and avoid the ligament injuries who are the typists, musicians ...