The Balance Ball Chair is an office chair and exercise tool that offers both health and fitness benefits. The Balance Ball Chair design combines comfort and back support, strengthening core muscles and improving spinal alignment. Removable 52cm Balance Ball can be used for exercises on or off the chair. For optimal performance, it may be necessary to re-inflate your new Balance Ball once or twice after the initial inflation for perfect fit. Designed for people 5'0" to 5'11" tall. Not designed to fit people 6'0" or taller, or 4'11" or shorter. Weight limit: 300 lbs.