DYNAFLEX Powerball Pro with PowerDock 4" high 3.5" wide Intermediate gyro hand exerciser bundled with gyro docking station Increases your range of motion and conditions your arm and shoulder muscles Reaches up to 11,000 rpm and creates 30 pounds of torque resistance Helps prevent and/or eliminate carpal tunnel, arthritis, and tennis elbow Docking station activates gryo within seconds; requires 2 AA batteries