Therapist&rsquo;s Choice&reg; Hand Exercise 3 Ball Kit: 3 Color Coded Resistance Levels 3 Ball Kit: 3 Color Coded Resistance Levels: Soft (Yellow), Medium (Blue), Firm (Black) Perfect for progressive training: Improves Strength, Prevents Stiffness and Relieves Joint Pain Reduces Stress and Eases Muscle Tension Develop and strengthen hands, fingers, wrists and forearms with a few simple, do anywhere squeezing exercises Made from TPR: Phthaletes-Free and Latex-Free