The Movin' Sit Air Cushion is an inflatable dynamic cushion which activates intrinsic trunk muscles to support the spine. The wedge shape encourages a seated posture with a forward pelvic position. It can also be used upright in any chair as a back support or on the floor. Adjust inflation to comfort level. 45kg (100lbs) max weight. Measures 33cm (13") diameter. Ages 3+.