The Cando Inflatable Vestibular Disc mimics both the movement and shape of the inflatable exercise ball when used on any seat. It acts as a dynamic cushion to activate major muscle groups. Use it on the floor as a standing disc for balance training, proprioception and strengthening of the lower extremities. You can also deflate to 1" thickness or inflate to 2" to make firm. Each disc has one nubby side for a tactile feedback and stimulation and a flat side. 300 lbs weight capacity.