The Gelbodies knee protectors use a pressure relieving gel, to provide 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 Should not be worn for longer than 12 hours at a time. Supplied in pairs SIZING: Measure circumference above the knee. Small: 23cm-28cm Medium: 28cm-33cm Large: 33cm-41cm Choose the larger size if measurement is between sizes