Therapist's Choice Hand Exercise 3 Ball Kit: 3 Color Coded Resistance Levels Develop and strengthen hands, fingers, wrists and forearms with a few simple, do anywhere squeezing exercises. They come in a set of three resistance levels, so you can gradually build strength and stamina to achieve a stronger grip. The balls can be heated or chilled for different applications. Set includes soft, medium, and firm resistances balls. Features: Made from TPR: Phthaletes-Free and Latex-Free 3 Color Coded Resistance Levels: Soft (Yellow), Medium (Blue), Firm (Black) Perfect for progressive resistance training Improves Strength, Prevents Stiffness and Relieves Joint Pain Reduces Stress and Eases Muscle Tension Size: Balls are 2" Round CAUTION: CHOKING HAZARD. Keep away from small children!