1It is made of durable, high-elastic materials, which is flexible and suitable for all ages. 2Because of the small size of the hand exercise ball, it can be carried in your pocket, and it can also be taken out to kill time on the trains or in the car. 3Using high elastic band, won't curb wrist, flexible rolling, not easy to slip off, convenient for use. 4Double row buckle, double fixation, you can adjust the size of the ring at will. 3pcs of exercise ball are available for use. 5Suitable for hand rehabilitation training, exercise strength and finger flexibility, activate the joints.