Oakley engineering takes performance to the next level and brings style along for the ride flak 20 offers a standard size frame with enhanced lens coverage and every millimeter of the lens is optimized with high definition optics174 in a ruggedly durable yet lightweight design designed to push your limits with patented xyz optics174 for razor sharp clarity and secure grip of unobtanium174 main featuresthe xl edition offers enhanced lens coverage and specialized lens curvature for th