How Photochromic Day Night Driving Glasses Work: Photochromic lenses turn light grey into dull grey based on UV intensity.It can deepen the color at any time outdoors except indoors and in cars with UV protective film on the windshield.It is not as dark as ordinary sunglasses,which affects vision and driving safety.It is superior to dark sunglasses,because when moving indoors or in low light,it will automatically adapt to low light conditions to make the vision more comfortably and clearly. UV400 Anti-UV Polarized Lenses 100% UV400 protective coating can block harmful UVA and UVB rays and protect eyes perfectly. TAC polarized lenses can reduce glare and reflected light of roads, water and snow, reduce eye fatigue, and make the vision wider, clearer and safer. It works like expensive prescription sunglasses, which can save you more money. Classic Sturdy and Durable Flip Clip Constructed by precision engineered spring bridge ,ensures smooth, solid and durable flip up that won't break or stick. Each leg of the clip has a rubber sleeve to prevent shifting and scratching glasses. You can turn it up when you're not wearing it, instead of taking away your eyewear, saving time and easy to wear.