Features:

Full internal floatation w/built in ventilation channels
100% glare free Polarized lenses by Polaroid
Wrap around frame for side UV protection
Integral retaining strap
Case included

The floating styles are equipped with Polaroid Polarizing lens, technical
name is S13. The support layers of this material is CAB (Cellulose Acetate
Butyrate). It is a 7 layer laminate with a high quality scratch resistant
hardcoating. The whole lens is presspolished and optically correct, optical
class 1, CE standard.

CAB has advantages and disadvantages...
+unbreakable
+99% polarizing efficiency
+100% chipping free
+optically class 1, power readings and refraction is excellent
-fairly scratch resistant 2.5 HD
+lightest weight
+very good thermal stability
-distortion along frame edges possible