Gaiam Classic Balance Ball Chair Ball - Extra 52cm Balance Ball for Classic Balance Ball Chairs OFFICIAL CHAIR BALL: This 52cm Balance Ball is made exclusively for the Gaiam Classic Balance Ball Chair models (Including Backless) as an extra or replacement ball (Chair NOT included) 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. REMOVE BALL FROM CHAIR FOR WORKOUTS: Remove the balance ball from the chair to perform core workouts and stretching routines INFLATION INSTRUCTIONS: For a perfect fit, it may be necessary to re-inflate the ball once or twice after the initial inflation to stretch to its final size. Inflate ball with air, let stand for 24 hours, deflate 50% then fill again to 52cm height.