Wirst sports crazy ball Wrist ball with NEON&counter Increase strength of fingers,wrists,hands, ... over 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 ... broken fitness exercise wrist exercise ball with light and counter