Made from wind resistant Poly/Lycrareg;, these arm warmers feature a gripper elastic hemmed bicep cuff and an elasticized, rolled-finish wrist cuff. The bicep cuff is specially designed for high intensity sports, preventing even the slightest slippage. Lightweight and easy to store, this handy accessory can come in handy on just about any ride or run. This garment provides all around compression and protection from the elements. Compression helps prevent fatigue in muscles and can increase power output. Bicep (Unflexed) Sizes: XS 7-8 inches (18-20 cm), SM 9-10 inches (23-26 cm), MD 11-12 inches (28-31 cm), LG 13-14 inches (33-36 cm),XL 15-16 inches (38-41 cm). These are general sizing recommendations. Sizes can go up or down a size depending on desired fit.