Martin Retro® Acoustic Guitar StringsMartin Retro strings are the real deal. Not an imitation. With Martin Retro strings, you get one tough set that offers true, consistent tone and sounds like nothing else on the market. Martins solid nickel copper alloy blend provides a reduced pick attack that allows the guitars tonewoods to be heard, not overshadowed. Martins proprietary Monel wrap wire is naturally corrosion resistant, so you can play them for a long time with nothing to get in the