Serengeti Flex combine the latest in style with unmatched comfort due to lightweight and flexible sunglasses designs. The comfort level of Flex Series by Serengeti is so high, you'll quickly forget you're wearing sunglasses. Serengeti Flex Series incorporates flexible metals into a unique hinge design that automatically adjusts to the contours of your head. Serengeti Flex-Series are equipped with the unmatched lens technology that Serengeti sunglasses are famous for. Flex sunglasses feature "S" shaped temple design ensured optimal flexibility and comfort. Although Flex sun glasses have the primary focus of comfort, the lens technology provides a viewing experience that is second to none. For the best of the best lens technology with Flex frame designs, see the line of Serengeti Flex Polar PhD.