Beautiful styling in addition to UV400 protection. Photochromic lenses are transformed from indoor reading glasses to outdoor reading glasses. They can also be used as ordinary photochromic sunglasses with UV protection. UV400 rated sunglasses is essential to protecting your eyes against long term UV damage and keeping your eyes healthy when you go out Sports Frame is Lightweight But, for Safety Eyeglasses with Wraparound Design that Provides Increased Side Protection and Peripheral Vision Note: This is not sunglasses! ! The photochromic lens changes according to the intensity of ultraviolet rays. The stronger the ultraviolet rays, the deeper the discoloration, and the weaker the ultraviolet rays, the lighter the discoloration. (We will check carefully before leaving the warehouse). Photochromic glasses have lenses that change tint depending on the weather or surroundings. The benefit of photochromic lenses is that in dull, overcast weather or darker surroundings (like running or cycling through woods or early / late in the day) they will lighten. But in bright, sunny conditions they will go dark. Photochromic lenses are most popular with cyclists, runners, skiers, tennis and outdoor reading enthusiasts.