Made out of pure biodegradable latex, the SZABALL is the best way to build a powerful but flexible grip. No more unilateral motion of the hand typical with the regular spring activated devices, which, by the way can cause tendinitis if not careful (I know…) Just squeeze the SZABALL with your full hand at your own pace making sure you alternate with the finger tips. Continue the exercise until you feel a warm feeling in your forearm and switch hand. Or, get two and save some time! Repeat every other day, and in no time you will notice you can squeeze the ball with greater range of motion and with less effort. Keep in the bag and away from the sun light when not in use. 100% made in the USA with American materials.