I had a couple of pairs of these and now use Uvex for cheap effective MTB sunglasses. The frame quality was worse on the later pair of Chinese fakes and after very bright, long days my eyelids feel suspiciously tight if I’ve worn them which they don’t for the Uvex.
I understand that there possibly shouldn’t be a difference in UV performance but it certainly feels like the certified units offer more protection. Then there’s the horror stories about the frames if you faceplant hard enough that broken glasses forcing their way through your face might be an issue.
I tried them, wouldn’t go back to them. In the grand scheme of things the real item isn’t expensive compared to eye damage, and there are plenty of 20odd quid choices that look good and are properly certified if you don’t want to spring £100+ for sunglasses (I don’t!)