Ordering here made me a bit hesitant at first. The deal seems too good to be true right? But it is legit, now I have an awesome pair of Costa 580g glasses for a great discount. The shipping was a bit slower than other sites claim, but I believe this has to do with the fact that the authentic glasses are shipped directly from a Costa store. Do not hesitate to purchase from Provengo, I am glad i did not. As to the glasses themselves, they are brand new so I can't speak to the durability over the long term, but they seem quite sturdy. And as far as weight with the glass lenses, it does not seem to be a factor at all for me. I really like the blue mirror, can see perfectly even without having any open blue water in the middle of Ohio.