Liveup SPORTS Exercise Grip Ball Silica Gel -Hand Strengthening Therapy Stress Balls Set of 3 PACKAGE INCLUDING 3 THERAPY BALLS: Three resistance levels included: soft (RED), medium (GREEN) and firm (BLUE), DIA:2.25". Find the perfect resistance for your needs! MATERIAL:The exercise balls are made of thermoplastic rubber (TPR) and they will keep their original shape after being repeatedly compressed. HAND THERAPY & RECOVERY:Prevents stiffness,increases flexibility,relieves joint pain,reduces stress and eases muscle tension. DAILY EXERCISE BALL KIT:It's good fordaily strengthening and keeps fingers, hands and forearms strong and supple. 100% QUALITY GUARANTEE:100% money back or a free replacement if you have any hassle with the item.