Sportime Abilitations Turt-L-Shell with 23-1/4 in. Dia is inflatable as well as water friendly. It offers great results in static and dynamic balance activities with hands-on therapy from a therapist. Turt-L-Shell helps in improving trunk control and is highly versatile taking ball therapy 1 step further. Turt-L-Shell can be inflated or overinflated for turning ordinary Dome into a dynamic half-ball that functions on any stable surface like floor mat table or chair or in the water.