About this item * This unique product is our standard "wobble cushion" that has an attractive, zippered, overlay that can be removed and washed. * Used as a wiggle seat to provide sensory input, and to help calm children that have a hard time sitting still. * Ergonomic seating, relieves back pain and shoulder aches. * Balance cushion provides an unstable surface to exercise on, requiring you to use more muscles to stay balanced. * Ships inflated, includes a pump for adjustments. Stability disc size: 13 inches / 33 cm diameter