Strengthen fingers, wrists, hands, forearms, shoulders and bicep etc., and also be beneficial in promoting co-ordination and blood circulation.
Rehabilitates sore muscles and joint, great for musicians, guitarists, pianists, drummers.
Small, compact and transportable, you can take anywhere. Simple to start with a pull-string.And the ball with flashing LED
All you need do is to increase the speed by making a rotational wrist movement and to keep in sync with the spinning of the ball.
The faster you spin the harder your muscles work.