Discover your guitar's true voice with MM11 Retro Acoustic custom light acoustic guitar strings are the real deal, not an imitation. With Martin MM11 Retros, you get one tough set of strings that will last a long time and give you true, consistent tone 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 tonewoods to be heard, not overshadowed. It offers uniquely mellow, yet crisp, sound. Martin's proprietary wrap wire is naturally corrosion resistant.