The Ultimate Performance Elastic Knee Support offers comfortable support for weak, stiff or aching knees with a breathable elastic mesh and tailored design to help prevent bunching behind the knee and ensure all day comfort. Lightweight knitting technology provides firm support while maintaining natural range of movement. Edge trim technology helps prevent slipping and reduces wear. The tailored shape prevents bunching behind the knee making it comfortable to wear all day. Fibre Content: 65% polyester, 35% rubber. Recommended for: weak, stiff or aching knees. Bilateral – fits left and right. SIZING – measure around the centre of the knee. SMALL 12-14″ (30-35cm) MEDIUM 14-16″ (35-40cm) LARGE 16-18″ (40-45cm) XL 18-20″ (45-50cm).