Serengeti Cosmopolitan Savona Sunglasses, Black Genuine Leather with Drivers Lens Base Curve: 6 RX; Temple Length: 128 m; Lens Size: 57.8 x 42 x 60.9 The Drivers brown-colored lens is ideal for driving, because it adjusts to the changing light conditions that are inevitably encountered on the road. 24% Transmittance lightened lens/9% transmittance darkend lens.