It is a grip strength trainer for adults, a physical therapy ball for hand spasm, arthritis, and stroke, a stress ball for mobile phone and computer enthusiasts, and a squeeze ball for people with ADHD. The football shape with four finger holes is more in line with the hand engineering design, easy to hold, the hole diameter is 0.9in, suitable for the finger exerciser of most adults. Strictly selected TPR silicone material, use at ease,Odorless, no easy to break. Size 4.7*3.9in, grip strength 10 pounds,easy to carry, easy to use, and can be used at any time. Beautifully packaged, it is your first choice gift for friends and relatives. Hand Grip Strengthening Exercise ball for 4 Fingers, fixed more firmly.The size is suitable for most people, especially for Athletes, Musicians & Physical Therapy.