Serengeti offers the world's best sunglasses; the photochromic technology allows molecules inside the lenses to adjust to light, causing them to lighten and darken automatically; A stylish choice perfectly suited for any element you're traveling on Base Curve: 8, Temple Length: 130mm/Spring HingesThe Drivers Gradient lens is the choice for pilots and anyone who requires eye protection in addition to crystal-clear view, as this lens provides exceptional clarity and confidence in all conditions - 24% transmittance lightened lens & 9% transmittance darkened lens