Expanding (literally) on Zeals award-winning Portal, Portal XL provides the biggest vistas ever. Packing all the same great features as the Portal, including ZealspatentedRail Lock System (//RLs), Portal XL provides a larger fit with more coverage for face shots. Its field of vision spans the widest of ranges and features its Optimum, Optimum Polarized, and Optimum Polarized Automatic Plus lens options. With a bonus, Persimmon Sky Blue Mirror lens included with every pair, and the Rail Lock Systems groundbreaking lens change system, the mountains just got a lot larger.The vertical Rail Lock System makes changing your lenses on the go a breeze, and it allows you to vent your lenses while hiking, or on the deepest, wettest days for fog-free skiing and snowboarding, which lets you keep charging while others are sidelined by fogged out lenses.