Kids stay calm and focused while sitting as the seat gives them an outlet for excess energy in the classroom, during meals and at homework time. Allow children to quietly move while working enabling them to be more productive. Flexible nubs on one side and smaller bumps on the other give a choice for just the right amount of tactile stimulation. Ergonomic disc causes the body to stabilize itself- improving posture. 13" /33cm diameter is a great fit for a seating while being large enough to grow as the child does. Effective on chairs, benches or directly on floors. Comes inflated and can be customized for each student's needs.