Product description:Color: blackMaterial: ABS + metalPackage includes:1 * gripperDescription:MULTI-APPLICATION: This 4-button finger training device was specially developed for many musical instruments such as guitar and trumpet. It also helps for your finger strength training.ADJUSTABLE TENSION FORCE: The individual finger tension is adjustable from 3 to 8.5 lb. You can lock 2 buttons at the same time, so you can choose different tension forces for each finger and choose the fingers that you want to exercise as you wish.UNIQUE & HIGH PERFORMANCE: The environmentally friendly silicone offers a good grip during training and the copper core spring offers good resistance for strength training.COMFORTABLE GRIP: Anti-slip granules on the silicone surface do not make it easy to slide off the palm. Groove design of the buttom makes a comfortable press.VERY PORTABLE: With a portable size, you can carry it in your luggage, bag, wallet, purse, etc. It is convenient for you to strengthen your fingers anytime you want.