CanDo? plastic ball chair includes either a 50 cm (adult) or 38 cm (child) inflatable exercise ball and chair base. The mobile ergonomic seating systems combine the benefits of ball therapy with the convenience of a chair base. Ball held securely in place by the base. Casters glide on carpet or hard surfaces. Light assembly required. The plastic ball chair is available in child and adult size. Locking casters sold separately.