Welcome to the world of active sitting and a chair that just might change your life. Gaiam's bestselling Classic Balance Ball® Chair provides all-day ergonomic support for a stronger healthier back. By sitting on the ball, you’ll improve your posture and spinal alignment while getting a powerful core-strengthening workout. Easy assembly required. Weight capacity: 300 lbs. Height: For those 5’ - 5’11”. 52cm balance ball. 22" x 31” x 22".