How it works: Unique three-layer construction; first layer is hydrolon terry which wicks moisture away from skin to keep you dry and comfortable. Perforated Hypolan blend middle layer is comfortable, cushioned and breathable, provides light compression which helps counteract tissue swelling. Durable nylon outer layer retains body's own heat, to naturally increase blood flow to damaged or painful joints and muscles to help encourage healing and pain relief. 3 1/2 inch extra wide with tendon pad. Loop-lock strap with elastic added for customized fit. Relieves pain and strain on extensor muscles. Fastens easily with one hand. Affordable. Long wearing. Provide firm yet comfortable support. Lightweight. Go anywhere support. Measure forearm circumference: SM 10 inches; MD 11 inches; LG 12 inches; XL 13 inches