At 13 inches in diameter this product is excellent for children as well as adults. This product is excellent for special needs children who lack sensory input or spatial awareness. The Sensory Seat can also be used as a calming agent for people with ADHD, low tone, or even simple lack of circulation. The use of this seat will improve awareness and lessen hand fidgeting. Unlike other seat cushions, the Sensory Seat does not need to be inflated. When finished, simply roll up the cushion, attach the included velcro strap, and place the seat pad in a book bag, hand bag, brief case, etc. This product is being used in school systems, therapy clinics, and even at dinner tables across the country. Who knew sitting could be good for you? Includes seat pad only. Stool sold separately however seat pad can be used on any standard stool, desk, or chair. Pad can also be used for a sensory floor pad to rest feet on. The SOS Sensory Seat is a Sensory University original design. All rights reserved.