All products on FSAstore.com, the Flexible Spending Account Site, are guaranteed to be FSA Eligible! Steel support hinges help prevent hyper-extension and provide side-to-side support. Sports neoprene for stabilizing compression and therapeutic warmth. Built-in superior horseshoe support controls patella alignment. Two adjustable straps. Color: Black Sizing: Measure 4" above center of knee Size XL fits 20" - 21