Lightweight combination 500 denier polyester mesh / 600 denier polyester for maximum ventilation.Velcro side cinch strap system allows for up to 2 expansion of waist.Oversized 13 cowhide leather on the knee for maximum durability, added grip and heat protection.Velcro / snap button front and YKK brand zipper for increased closure security.Mesh ventilated front paneling for added airflow.Rear yoke stretch system allows the pants to stay in place.2-way spandex in the knee, calf, and crotch provide added flexibility and accommodate protection.Athletic, race fit provides unrestricted movement.