The D'Addario Dynaflex allows you to achieve the competitive edge no matter what instrument you play. This handheld gyroscope builds and conditions hands, wrists, and forearms while also increasing hand speed and endurance. It's like having a personal musician's gym in the palm of your hand. Simply start the rotation and then with a rocking motion, build up the gyroscopic speed for a full hand and forearm workout. Great for keeping the playing muscles toned when away from your instrument or for pre-show warm up. Use in conjunction with the D'Addario Varigrip for the complete finger, hands, and arm workout.