Lens fog is a performance killer, so Oakley developed a three-tiered defense. First, they devised surge ports to control airflow. Second, Oakley formulated F-3 Series anti-fog treatment. Third, they engineered a dual lens design to reduce fog with a thermal barrier of trapped air. Then Oakley took all that technology and juiced it with the precision of High Definition Optics® (HDO®), topping it off with a wish list from the pros: 100% UV filtering, impact protection that meets ANSI Z87.1 / ASTM F659 standards, durable urethane that stays flexible, and comfortable triple-layer polar fleece foam with moisture wicking.