The first time I ordered these I was confused about the numbers and sizing of the glasses, and got it wrong. Here's how it works:
The glasses come with either a 50mm or 54mm lens diameter. I can't say whether they're just wider or are also taller, as I haven't tried both sizes.
They also come with a choice between two different distances between the lenses: 18mm & 22mm. I guess if your head is large, you'll probably want the 22mm option.
Model Number Explanation, as far as I can figure. Haven't quite got it down, but this should be close:
The set I own now: 902/57-5022
The first set of numbers is the color/style, ie: Tortoise frame = 902. The number after the slash seems to correlate with lens type, ie: Crystal Brown Polarized = 57. Therefore, 902/57 style is a Tortoise frame with Crystal Brown Polarized lens.
The second set of numbers is a little easier. The first two numbers are the lens diameter and the last two is the distance between the lenses, ie: 5022 = 50mm lens with 22mm between the lenses.
FYI: This style, 2140, is the "Original Wayfarer" style. Others include the 2132 (New Wayfarer), 2151 (Square Wayfarer), 2143 (Wayfarer II), 4105 (Folding Wayfarer), and the 9035 (Junior Wayfarer for kids).
I hope this helps!
The glasses do fog up easily, at least on my face. I believe it's because they are closer to my face than regular sunglasses. For that, and the lack of easy explanation of the styles and sizes, I subtracted a star, but I love the way these glasses look and wouldn't part with them for anything!
<edit> The New Wayfarers (2132) differ in that the lens is more shallow, so if your cheeks hit the classic Wayfarers, they probably won't with the new style. Also, the New Wayfarers have slightly thinner & lighter plastic frames. I prefer the New Wayfarers myself, but they don't make the frame/lens combination I like (Tortoise/Brown Polarized) in that model.
<edit 2> See Amazon Blonde's comments below for a correction and clarification to the explanation above.
Also, if you like the style, but not the way the Ray Bans are constructed, Maui Jim makes a more subdued, but better-made frame with the model number MJ242, sold at Sunglass Hut. They fit me better and have spring-loaded bows, which is nice. Also, they have rubber built-in to the nose, but invisible. They also don't hit my eyelashes like the Ray Bans do.