Suitable: This 5-button drill is specially designed for many kinds of musical instruments, such as guitar, trumpet. It also helps strengthen the fingers. Adjustable Tension: Individual finger tension is adjustable, ranging from 3LB to 8.5LB. You can lock 2 buttons at the same time so that you can choose a different tension for each finger and choose the finger you want to exercise at your convenience. DURABLE: Eco-friendly silicone provides good grip during exercise, copper spring provides good elasticity for strength building. Comfort: There are anti-slip particles on the surface of the silicone, which are not easy to slip off the palm; the groove design at the bottom makes it comfortable to press. Portable: With portable size, you can put it in your luggage, pocket, purse, purse, etc., and keep your fingers strong anytime, anywhere.