Set includes 24 SitRight covers and stability balls, making it easy to equip the entire class with padded self-righting active seats that improve posture and concentration! Thick mesh cover is extremely durable and rights itself so students don’t need to roll and “search” for the padded top. Design also provides a more comfortable seat than traditional hard classroom chairs. Cover protects the 55 cm ball from damage and easily secures via hook-and-loop fasteners. While seated, students can grab the 2 side handles for extra stability; handles also make it easy to move and store the ball. The ball fits Jr high students or students between 4'8" and 5'4"H.