【Different hardness hand trainer ball】 Finger trainer hand trainer has 2 different degrees of hardness and design. The blue ball is for soft resistance (10 pounds), the yellow ball is for medium resistance (25 pounds). 【Washable hand training ball】 The hand trainer balls are washable and can be cleaned with water as usual after use. With round, this anti-stress hand ball adapts perfectly to your hand. 【Durable and robust — anti stress balls】 The ball hand training devices are made of high quality elastic PU ＆ silicone and keep their shape even with frequent use. Our hand exercise balls are uniquely designed for long-term and frequent use. 【Rehabilitation and Prevention】 When you are fit or using the computer, the muscles of your hands are accidentally tensed or sprained. Then this workout kit is what you need to get your hands and fingers rested. 【Ergonomic Design For All Hands】 The strength trainer is ergonomically shaped and fits well for all hand sizes and all age groups, ideal for men, women, seniors and adolescents.