The inflatable vestibular disc 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. It can be deflated to 1"thickness or inflated to 2" thickness. Each disc has one nubby side for tactile feedback and stimulation and one flat side. This is a great tool in the classroom for children with ADD and Autism. The disc is 35 cm in diameter (13.8 inch).