Gyro Ball Forearm Exerciser Wrist Exercises Wrist Ball Hand Exerciser Effect is equivalent to 50 different weight dumbbells, Improve your hand, wrist, forearm and shoulder strength Shell uses import original and high strength transparent PC material, Precisely balanced Easy to start with starting copper head rope With a digital counter, Simple and easy to replace batteries, Don't open circuit board With a digital counter, Simple and easy to replace batteries, Don't open circuit board