Gaiam Classic Backless Balance Ball Chair &ndash; Exercise Stability Yoga Ball Premium Ergonomic Chair for Home and Office Desk with Air Pump, Exercise Guide and Satisfaction Guarantee ALTERNATIVE DESK CHAIR: Same ball and chair as our best-selling alternative desk chair created by leading health & fitness experts to improve back health and core strength, but without the back support bar, encouraging better posture throughout the day BOOST ENERGY LEVELS: Using the same ball as the exercise guide, this chair helps to build a healthier core, align the spine, relieve back pain and stiffness, boost energy levels and increase productivity with an active body and a focused and engaged mind RECOMMENDED USER HEIGHT: Designed for users 5' to 5'11" tall and fits most standard-height desks. For a taller chair, add 2 inches with Gaiam's compatible leg extenders, sold separately. 300-pound weight capacity. INCLUDES: Removable 52-centimeter charcoal exercise ball, an air pump, an adjustable metal support bar, 4 easy-glide casters (2 back wheels lockable), and a desktop exercise guide to stay active INFLATION INSTRUCTIONS: It may be necessary to re-inflate the ball after initial inflation to allow the balls material to stretch to its final size. Inflate ball with air, let stand for 24 hours, deflate 50% then fill again to 52cm height.