CR39 is the abbreviated name of the lens material. CR39 is a plastic optical lens material with a refractive index of 1.498 (usually rounded to 1.5). It is the most commonly used plastic lens material. CR39 has replaced glass lenses as it is much lighter in weight and is safer than glass as it won't shatter or smash if dropped. Like all plastic lenses, CR39 is softer than glass and will scratch easier but it is difficult to smash.
Wikipedia says it better than I can. http://en.wikipedia.org/wiki/CR-39
Maybe 2003
rayban
RayBan RB 2132 Wayfarer sunglasses
GSM label in RayBan sunglasses stands for Gradient Silver Mirror. This is mainly found in Polarized models, where the upper zone of the lens is darker than the bottom (in a gradient way), and the exterior side (opposite from where you look when wearing on them) has a silver mirror effect.
Rayban waffers
The rayban sunglasses 660 is the colour brown tinted tan.
There are many places where one could purchase Rayban Aviator sunglasses online. The best place to purchase Rayban Aviator sunglasses would be places like Amazon.
Rayban
RB2140 (RAYBAN) Original Wayfarer
Rayban Aviators
Yes, Ray-Ban sunglasses do block UV.
It depends. Most large sunglass companies like RayBan install high-end sunglass lenses into their glasses and have been doing them for years.Do I think these lenses are better that the ones that are out now? No, but I think some eye protection is better than none.