1、MULTI FUNCTION: The self starting wrist ball can not only relax and reduce pressure, but also exercise wrist force. 2、EXERCISE MUSCLE: Rotate the wrist to feel the strength of the shaft, which can not only exercise the flexor muscle, but also coordinate yourself. 3、SUITABLE SIZE: The size of the wrist ball is suitable for the palm of most people and is easier to grasp. 4、RELIABLE MATERIAL: The wrist exerciser ball is made from premium alloy, PC and silicone, which is hard and sturdy, anti slip. 5、COMPACT AND PORTABLE: Auto start wrist strengthener is compact in size, very easy to carry wherever you go, play and exercise at any time. Item Type: Wrist Trainer Ball Material: Alloy, PC, Silicone Diameter: Approx. 70mm/2.8in 1 x Wrist Trainer Ball