With the great wrist strengthening ball, you only need to push the core in the direction of the arrow, to start your exercise anywhere. Small and lightweight, with the novel design of LED lights, you can see how fast the rotation speed is. When rotating, the LED lights up. The faster the rotation, the brighter the LED light, as long as it rotates, it will remain lit. The light will only illuminate when your speed is fast enough.A great option for training your fingers, wrists, hands, forearms, shoulders, or to increase your arm strength.