Powerball Supernova Models Gyroscopes - Wrist Strengthener, Grip Strengthening Gyro Ball (Supernova Classic)

Your Arms Won't Believe Your Wrists
From the tips of the fingers, into the hand, through the wrist joint, up along the forearm into the bicep and culminating in the shoulder, there isn't a single muscle or tendon in the arm that escapes the smooth but punishing inertial resistance generated by a fast spinning Powerball - the faster you spin the more power it generates and the brighter t...