3M Smart Lens Protective Eyewear, 13407-00000-5 Photochromatic Lens, Black Frame  (Pack of 1) Photochromic lenses darken and lighten as the outdoor light changes Spring-adjusted temples allow for a flexible fit on narrow or wide faces Strong frame with magnesium alloy temples provides durability Soft, adjustable nose bridge and nylon brow enhance comfort Polycarbonate lenses absorb 99.9% UVA and B