This knee protector is also comfortable and suitable for road racing and street riding duty, either under your pants (jeans) or leather suit. One size fits all. Articulated protector follows the movements of the knee joint. Impact resistant and ventilated thermoplast shell with aluminum reinforced. knee cup for superior energy absorption. Alpinestars Bionic Knee Protectors Ergonomically designed to fit the knees and the side of the bike with an asymmetrical form. Removable and impact resistant bio-foam padding with a comfortable. Lycra liner. Adjustable Velcro® straps strategically placed to prevent skin abrasions. Durable billet aluminum hinges. Snap assembly for easy cleaning.