Used while standing or lying on the floor, the dome shape and unevenness of the cushion add an element of instability, maximizing effort and enhancing results. This inflatable, dynamic air cushion that mimics both the movement and shape of a therapy ball. The Disc O Sit Balance Cushion is professional-quality and made from tough, durable, latex-free PVC vinyl that is virtually indestructible. It can also be used on the floor for balance training and strengthening of the legs & hips. The smooth bumps provide a tactile experience and can help improve difficulties with tactile defensiveness.