The Schiek Model 1136ES Elbow Sleeve supports the elbow and is made with breathable neoprene which is washable and expels moisture. The sleeve is made with reinforced stitching. 
 
For sizing, measure around your flexed bicep:
 
12" - 14" = Medium
18" - 20"  = X-Large
 
Please note that the elbow sleeves are sold as singles.