Polar?? lenses are polarized scratch-resistant lenses that deliver 100% UV A&B protection. Polar?? lenses are extremely light weight, durable and provide crystal clear visual acuity. Polar?? lenses reduce harsh glare with zero distortion, an important point when wearing a sunglass over corrective lenses. Gray lenses provide natural color definition, amber lenses improve contrast in low light conditions and yellow provide the highest level of contrast. Polar?? lenses are absolutely the best lens available in a fit over sunglass in the 40$ price range.