The Martin Retro Monels are throwback strings with a tone that works perfectly for fingerstyle players or anyone looking for an old-school tone! Retro strings offer a uniquely mellow, yet crisp sound that allows your guitar’s natural tonewoods to be heard. They are crafted with Monel, a solid nickel/copper wrap wire - not nickel-plated - meaning there is no chance for defects in the plating to allow for corrosion. Martin’s proprietary wrap wire is naturally corrosion resistant and it is incredibly strong. Martin also employs a sophisticated winding process that controls the coupling between the core and wrap wire to maximize intonation.