Toymarketing International Gymnic Sit'n'Gym 55 - Red Sit 'N' gym plus ball has little feet to prevent them from rolling away when used as a sitting ball Sit 'N' gym encourages dynamic sitting through Gentle body movements that improves blood circulation. It also promotes proper body alignment for better posture Adults can use it as an alternate chair when working at their desk An also be used as a regular exercise ball Made of heavy duty vinyl; inflation by adult