Photochromic sunglasses may sound a little puzzling to you. It's okay. A few words for its explanation will not be amiss. In short, photochromic means something that changes color in response to light. Photochromic sunglasses are that kind of sunglasses whose lenses darken on exposure to ultraviolet rays. Once you are free from the influence of UV rays, for example when you walk indoors, the lenses will little by little gradually return to the original clear state and vice versa.

Having a fairly clear knowledge of photochromic sunglasses, you must be astonished by human's intelligence and innovation. How amazing that would be! Exactly! Photochromic sunglasses have put to rest many hassles brought about by constantly switching between prescription glasses and sunglasses. Now with the aid of photochromic sunglasses, you are emancipated from all these nuisances. What a relief! But every coin has two sides, and photochromic sunglasses are no exception. In the first place, it, unfortunately, takes a little bit longer for photochromic sunglasses to clear than it does for them to darken. Sometimes when you walk indoors, your sunglasses will not instantaneously clear, often with a couple of minutes' time lag. And sometimes you will find your sunglasses remain clear after you go into your cars, which is because photochromic sunglasses react to ultraviolet rays and windscreens always block UV rays. After all, the advantages outweigh the disadvantage. Setting aside all these shortcomings, photochromic sunglasses are a brilliant solution for people who need different glasses for different situations. In a word, a pair of photochromic sunglasses will be of tremendous use to us.

How to choose photochromic cool sunglasses still remains a hard nut to crack. In general, the lens type crowns the list. It has everything to do with the sunglasses' ability to automatically adjust. Then you shall look into a reliable source of photochromic lenses. Firmoo, as a typical example of great quality and cheap glasses online, is providing its customers with a wide variety of photochromic sunglasses with improved safety, strong impact resistance and more fashionable styles. All your wishes are duly taken care of here. Make haste to garnish your face with one!