If you want true vintage sound from your acoustic guitar, you want a set of Martin Retro strings. 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 way of your music! This is a set of light gauge, 12-54.