The Sit 'N Gym Plus has little feet to prevent it from rolling away when used as a sitting ball. Widely used in European kindergartens and classrooms, the Sit 'N Gym Plus encourages dynamic sitting through gentle body movements that improve blood circulation and increases attention span for better learning. It also promotes proper body alignment for better posture. Made of super strong, latex free vinyl material and is surface washable. Booklet, extra plug and inflation device included. Maximum sustainable weight up to 270 pounds.