The Firm Slim and Sculpt Stability Ball with DVD
"Simple, versatile, and fun to use, the Firm Core Stability Ball is designed to challenge your balance, stability and flexibility through various low-impact exercises and movements. Included with the package is a 30-minute core training video that guides you through a variety of techniques that you can adapt to your training, stretching, rehabilitation or other workout routines. The ball is made of tough, burst-resistant plastic, a special material that resists tearing and, if punctured, deflates safely and gradually.  Available in several fashionable colors, and sizes:  55-Centimeter (Pink) is recommended for users measuring between 5 feet and 5 feet, 5 inches. 65-Centimeter (Green) is recommended for users measuring between 5 feet, 6 inches and 5 feet, 11 inches. 75-Centimeter (Purple) is recommended for users measuring between 6 feet and 6 feet, 3 inches."