Kind of pricey, but WOW. These are without a doubt the best photochromic lenses I have ever used. Huge range in VLT and they transition really fast. Even in full sun they are really good. I was not expecting them to be this good, but now I might be bringing these along on more rides.
As a total optics nerd I have tried almost every major brand out there, but I always come back to KOO. This lens is no exception. My other fav lens is the fire lens becuase it actually does pretty well in lower light unlike many other red/fire mirror lenses. Def worth a try for MTB or if you have a lot of sun/shade on rides.
The lenses on 1 of my 3 Jawbreakers started degrading. At first I noticed little white spots in the Prizm film and then a section looked like a jigsaw puzzle. Surprisingly for the most part they were still functional. It seemed mostly cosmetic, but it did make them look OLD and I wondered how long before it would impact the vision and/or be extremely annoying. I decided to get the replacement lenses to refresh the look since my frames looked new. I take very good care of my eyewear and only use my Jawbreakers for cycling. They are immediately stored in their case after every ride. I am careful to only use the included cleaning cover to ensure they don't get scratched.
I take very good care of my glasses. I only use them for cycling. I actually have 3 in different colors that I rotate based on riding attire. Over many years the lenses on my first one developed little white/clear spots on the film that were actually not visible while in use. After that the coating/film on the inside started deteriorating. I am not sure how to explain but it was like a small jigsaw puzzle. Surprisingly when you wore the glasses it was not obvious, but when you took them off you could see how they would probably fail in the near term. Since I took care of my glasses the frame was in excellent shape. Once I installed the replacement lenses (easy) I ended up with what I consider a brand new Jawbreaker at half the cost.
Still generally prefer the shape and design of the Koo Demos for my whopper head, but I find the frame bottom of the Demos to impede vision a bit. That's why I bought the Alibi. Unfortunately the Alibi is a bit narrower across the lenses, and the temple is perhaps a bit short so the glasses want to fall forward and down. Works great with the Kask helmet, much better than other brands. It's better than most and probably ideal if your head doesn't fill a 10 gallon hat.
