Develop hand strength and dexterity with 66fit Set of Two Hand Resistance Balls. 66fit Therapy Massage Balls are widely used in rehabilitation and sports/ exercise environments alike. Use the two varied resistance balls as part of a progressive resistance training programme following accident or injury to help build up strength and dexterity in the hands and fingers. The exercise balls are ideal for developing wrist movement and flexibility post-surgery increasing muscle tone and strength in the targeted areas. In addition, used in a fitness environment the 66fit balls can help train the forearms, hands and fingers to increase general strength and dexterity hence improving grip and functionality.