I believe that all masks are made with tempered lens so, I don't think that is an issue. I personally think that the difference in the mask is all in the skirt. PVC with silicone vs. all silicone. PVC when exposed to sun and chlorine or salt water will break down and could leak because of cracking in the skirt after some use. My concern would be that while diving, your mask could have a major leaking issue possibly causing you to have to ascend without a mask.