Smith Optics Guides Choice XL Tortoise PolarChromic Copper MirrorPrimary Lens: Glass Polarchromic Copper Mirror Designed as a fly fishing lens for the mountain streams of the Rockies, Smith Optics Techlite polarchromic copper lens is one of their most versatile, robust and high contrast lenses. Techlite glass lenses have maximum clarity and provide up to 12x more scratch resistance than a polymer lens, and can be up to 20% lighter than a traditional glass lens. These sunglasses have a Tortoise Frame. Vision