Nano2 stands for a "squared" shaped lense. It best fits a large to extra large profile. The Nano2 comes with Interchangeable Lenses, a Venting frame, and Cushions for your nose. There are 4 sets of lenses for all light conditions: 1. Polarized for superior glare reduction. 2. Orange Crystal: 57% VLT for medium light. 3. Yellow Crystal: 80% VLT for low light. 4. Clear Crystal: 98% VLT for very low to no light. All lenses offer 100% UV protection(including yellow, orange and clear). The total weight of the sunglass is 0.90 oz.