Rolling and bouncing fun! The SensaTrak roller is made from heavy-duty vinyl (wipe clean) and is designed to move from slight movement. It includes ridges and plastic balls for extra sensory input. Weight limit: 36kg / 5stone 7pounds. Inner diameter (i.e. where the child sits): 99cm / 39inches. Suitable for indoor and outdoor use, but please keep away from steep gradients and sharp objects!