Only buy if your after a cheap pair of glasses that look good but won't last. I bought a pair of dark grey k3 sunglasses with the yellow/red lenses. A also bought a photochromic lens as the discounts offered by siroko are very reasonable. All seemed well until I tried to change the lenses out and replace with a different pair. It is very difficult and requires an uncomfortably large amount of force to remove and reinsert lenses to point when I was worried about damaging the lens surface. After 5/10 minutes of trying, the tops of the lenses had been chipped as there was no other way of reinstalling the lenses without causing some minor damage. After this I accepted not to take out the fancy yellow lens until they were damaged enough that I'd throw it away. This, as it turns out is very very easy to do. Even the simple act of cleaning the lens after a ride with lens cleaner and a brand new cloth will result in fine scratches all over the lens surface front and back. The plastic itself feels cheap and brittle, to the point where just putting the glasses on would result in creaking and clicking from the frame. After 6 months my experience with these sunglasses came to an end this past weekend when I was about to tackle a ride, I went to put them on and they snapped under next to no pressure at all rendering them and the extra set of lenses I bought useless. These sunglasses do work, they are polarized and they do look good and with regular discounts, you could bag a bargain. If that's all your after then go for it. However, if you want a pair of reliable cycling glasses that won't brake or cause problem I'd invest in something a bit more expensive and go somewhere else.