Just place these handy cushions on the floor or on a chair—for flexible seating anywhere! Our super-durable vinyl cushions are specially designed to let students wiggle and wobble while they sit…helping children focus as they move. The cushions feature large nubs on one side and small nubs on the other—students simply select the sensory surface they prefer! Cushions require inflation with a standard ball pump (not included). Cushions measure 13 1⁄2" in diameter.