600 denier nylon outer skin^ EVA foam padding^ PP protective shells and splint^ Adjustable velcro straps * Specs: 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.