MX O FRAME ENDURO ACCESSORY LENS Best for low-light environments, this Clear lens includes anti-fog treatment on the inner surface. That’s just the start of its fog-cutting performance. Fog buildup occurs when moisture vapor from your skin comes into contact with a lens cooled by air temperature and wind. This design uses two lenses and puts an insulating layer of air between them. It gives you the ultimate in fog protection, along with unsurpassed clarity and impact resistance. Important Note: Use care when installing/removing accessory lenses. Scratched lenses can not be returned and are not covered under Oakley’s warranty policy.