they seem just as sturdy as my frog skins, as far as hinges go. glass isn't anywhere on par with a pricier pair of sunglasses. you should check out these too, http://shop.fortresseyewear.com/
Frames are nice, lenses are pretty good. Obviously oakley has better optics but for $15 you cant go wrong. Get a few so if you lose/break them you have a couple spare, and you can switch the lenses fairly easy with a hairdryer and a bit of force.
posted this in another thread, but i am wondering how they compare in size and fit in holbrooks, since holbrooks are the only type of that style of glasses (frogskin/jupiter for example) that dont look retarded when on my face.