Oppo: Biomagnetic Elbow Support OP2685. Helps to reduce pain due to tendonitis and Tennis Elbow. Permanent magnets give optimum effect on acu-points along the elbow. Made from breathable neoprene with cotton inside lining for extra comfort. Size: Measure around the elbow joint: 23.2-26cm Small, 26.7-31.1cm Medium, 31.8-37.5cm Large, 38.1-40.5cm X Large.