The inflatable vestibular disc mimics both the movement and shape of the inflatable 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. Can be deflated to 1" thickness (mushy) or inflated to 2" thickness (firm). Each disc has one nubby side for tactile feedback and stimulation and one flat side.