Discover your acoustic guitar's true voice. MM102 Retro Extra Light 12-String Guitar Strings are the real deal, not an imitation. With Martin MM102 Retro 12-string acoustic guitar strings you get one tough set of strings that will last a long time and give you true, consistent tone that sounds like nothing else on the market. Martin's proprietary SOLID nickel/copper alloy blend provides for a reduced pick attack which allows the guitar's tone woods to be heard, not overshadowed. It offers uniquely mellow, yet crisp, sound. Martin's proprietary wrap wire is naturally corrosion resistant.