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