MAXSOINS Power Essential Spinner Gyroscopic Wrist and Forearm Exerciser,Crystal Models, Llluminated, No Tachometer Weight: about 270 grams,Diameter: about 7.8CM.Powerball Gyro super ball that power, crystal models with lights, no tachometer,Grey Simple to start with a pull-string (included) ,A fun and relax way to relieve some stress Wrist, arm strength training, prevention mouse hand, refers to the force, grip strength training, Alzheimer's prevention Great way to build forearm strength and coordination,ease the shoulder ache caused by sedentary Improve your hand, wrist, forearm and shoulder strength,great for golfers, tennis players, bowlers, rock climbers and any sport where grip strength is the key