The Fat Boy photochromic sunglasses feature transitional lens technology. This photochromic technology is caused by molecular reactions to UV light that allows the lenses to darken reducing the amount of light reaching the eyes. The lens transmission allows 87%of light through indoors & allows 47% of light through outdoors. Featuring anti-fog, polycarbonate lenses. Increased comfort & protection with closed-cell memory foam around the eyes. The microfiber storage sleeve can be used for lens cleaning.