Native Eyewear Hardtop Polarized Sunglasses come with interchangeable lenses (the lenses that are in the sunglasses and one other pair) that allow you to adjust your outlook to fit any light condition. Polarized lenses reduce glare for improved visibility on bright days. If you need better contrast in low-light conditions throw in the Sportflex. For a nighttime trail run, snap the clear lenses into the wrap-around frame and protect your peepers.