Markwort Knee Pads 1/2" pad, 100% polyester covering of 9mm compound foam padding for maximum shock absorption. Polyester rayon and elastic knit back. Pad Size Knee Circ. XXS 4" x 5" 5-8" XS 5" x 6" 8-12" S 5.5" x 6" 12-15" MED 5.5" x 6.5" 15-18" LGE 6" x 6.5" 18-21"