Initially the ball may seem too small for the chair. 42-48 hours after the initial inflation. the ball will "relax" and you will be able to top off the air to full size. This is normal. * Created by leading health and fitness experts to improve your back health * Employs the same balance ball used in your workout routine * Helps build a healthier back, align the spine, relieve pain, and improve your overall well-being * Includes removable 52-centimeter Balance Ball, an adjustable support bar, easy-glide casters, air pump * Designed for users 5-feet to 5-feet, 11-inches tall; 300-pound weight capacity