The Thermoskin Elastic Elbow Support is anatomically designed with no seams. The Elastic support will comfortably contour to the shape of your elbow. It provides even compression and support for weak and injured elbows, while minimizing bunching. Sizing Guide: Measure circumference around elbow joint with arm extended. Small 7 3/4 - 9 inches. Medium 9 - 10 1/4. Large 10 1/4 - 11 1/2. X-Large 11 1/2 - 12 1/2 inches.