Wrist Trainer Ball Auto-Start Gyroscopic Forearm Exerciser Gyro Ball for Strengthen Arms, Fingers, Bones and MusclesAutomatic start design, need to push the core in the direction of the arrow, start by the internal spring, very easy and convenient. When it rotates, the cool colored lights inside will light up. It can kill time and add fun while restoring muscle soreness. Without any strange vibrations, it can rotate for a long time without worrying about it stopping when moving. The convenient design can be carried anywhere, whether in the office, gym or at home,