Prizmtrade trail flak 20 xl the xl edition offers a standard size frame with enhanced lens coverage and every millimeter of the peripheral view is optimized with high definition opticsreg in a durable yet lightweight design that takes performance to the next level and brings style along for the ride essential gear for competition flaktrade 20 xl has 875 base lens curvature for protection against sun wind and impact and patented xyz opticsreg maintains clarity along the full curve