The Alpinestars Bioflex Knee Protector Black is part of the latest collection from Alpinestars.. A lightweight slim protector which has been designed to offer high levels of protection while being discreet enough to be unnoticeable off the bike. Cell structure ensures maximum airflow, with an adaptive shape for excellent comfort, on and off the bike.• Ergonomic design that allows high levels of movement• Cell structure ensures maximum comfort and ventilation• Slim design makes the protector discreet off the bike• Protector cells are bridged together, allowing for an adaptive shape and enhanced levels of comfort and protection. View all Alpinestars. View all Alpinestars Accessories..