You might have gallons of brine in your face and 600 pounds on your hook, but the Costa Del Mar Blackfin Sunglasses still won't slip. The Hydrolite co-injected lining takes care of that, and the flexible frame means serious comfort. The Blackfin pushes the edge in sunglass performance. A Nylon frame ensures durability, while the integral hinge allows for easy on/off access. This pair of Blackfin's features the Costa 400 Lens, which is designed for adventure and built to perform with superior clarity, contrast, and definition. The Durable 400G Lenses are made of LightWAVE glass that's 20% thinner and 22% lighter. With a Blue Mirror lens tint, these glasses are made for the open water. Blue Mirror delivers maximum contrast and color in full sun while eliminating glare, and allows a minimal 10% light transmission. Every pair of Costas features 100% polarized lenses, providing complete UVA, UVB, and UVC protection, as well as a lifetime warranty against defects in materials and workmanship.