The Costa Del Mar Cut Polarized Sunglasses are made of heavy duty TR 90 nylon frames and has an internal hinge. The lenses are polarized with Costa's 580 technology that kills reflected glare and reduces eye strain. When you're wearing these classically-styled sunglasses, it's a lot easier to put your line right where you want it. The Copper lens is for driving and variable light. The Grey lens is for everyday natural contrast.