The Gelbodies protectors use a pressure relieving gel, which is found in high end wheelchair cushions, to offer additional padding to points on the body where pressure sores tend to form. The addition of padding to these areas improves circulation to those points by evenly distributing the body weight in those areas. By improving circulation, the Gelbodies protectors not only help to prevent pressure sores from forming, but also provide the patient with added overall comfort helping them to relax. Should not be worn for longer than 12 hours at a time. Measure around the ankle above the malleoli (the two protuberances). Small. 20cm - 25cm Medium. 25cm - 30cm Large. 30cm - 36cm. Choose the larger size if measurement is between sizes.