Just thought I should put this out there as a warning: if you're looking for the Smith Optics Turntable sunglasses that Walt wears, watch out, because there are now fakes being put out there. I acquired one such pair recently, and, after comparing them to another pair of Turntables that I had, found several differences between the two.

^ In this comparison, the fake ones are on the left, real ones are on the right. Notice that the lenses on the fake ones have a more round curve than the real ones.

^ Here, fake ones still on the left, notice the nose rest is shaped differently than the real one. You can also still notice the rounder lens shape here.
^ In this side-by-side, notice the fake ones (left) have a lighter tint than the real ones do. You could see the whites of my eyes pretty clearly when I wore the fake ones.
Another thing to be on the lookout for: these fakes had no imprinting or writing inside of the arms of the sunglasses. This might be understandable if they are in used condition, as the lettering could have rubbed off over time, but if someone is trying to pass them off as "new" or hardly-worn, there should be something written on the inside of the arms. I will use a picture Pitbull has posted in this thread previously as an example:
The last thing I did to erase all doubt that I was looking at counterfeit Smiths (as if all this wasn't enough) was that I mailed in the shades to the Smith Optics warranty department and asked them to confirm or deny their authenticity. They got back to me with the obvious news today: they are fake. So, if you care about authenticity, just know what to look for on your hunt for these shades.