Serengeti Cosmopolitan Vittoria Sunglasses, Shiny Tortoise with D Polarized Lens Approved for the Serengeti Custom RX Program. With its versatile brown lens, the Drivers Polarized lens peforms under cloudy and harsh light conditions. Plus, you get the added protection of the Serengeti polarizing technology. 18% transmittance lightened lens/10% transmittance darkened lens.