"NAGS" is aftermarket glass not manufactured by the Mercedes Benz or made for Mercedes Benz / it would be like buying a part from an auto parts store / not the dealer . If you notice on your windshield now , there is a Mercedes Benz logo on the glass / aftermarket glass is generally made in China, for cost savings / if you grt a/m glass look across the glass form the side of the car to spot any defects, usually waves or bubbles in the glass.