The removable, anti-burst Balance Ball (55cm) is free of latex and the six most harmful phthalates. Also includes redesigned base that cradles your ball, easy-glide casters, air pump and exercise guide. Easy assembly required. Available in black ball and base. 31½ "H x 20½ "W x 25"D; 13 lb. Included in your Balance Ball Chair System: A 55cm (22") Balance Ball, removable for exercise on its own. Easy-glide, lockable, castor wheels Air pump