600 denier nylon outer skin^ EVA foam padding^ PP protective shells and splint^ Adjustable velcro straps * Durable 600 Denier Nylon outer skin.; Comfortable 9, 13 & 18mm EVA Foam padding; High-impact PP protective shells and splint; Adjustable velcro straps; Open back knee pad design allows you to put pads on without taking off shoes * Sizing Chart: XSmall = under 4"6 inches; Small = 4" 6 inches - 5"; Medium = 5" - 5"6 inches; Large = 5"7 inches - 6"; XLarge = 6"+ * Pads should fit tight and not move around during a fall.