The Martin MA535 Traditional Phosphor Bronze Acoustic Guitar Strings aren't fancy, but they offer a clean tone and longevity. They're part of Martin's Traditional line, which is its flagship guitar string. Their core is tin-plated steel wire, and the wrap wire is Phosphor Bronze. Note Gauge (in.) Material E/1st .011 Plain steel B/2nd .015 Plain steel G/3rd .023w Phosphor bronze D/4th .032 Phosphor bronze A/5th .042 Phosphor bronze E/6th .052 Phosphor bronze FEATURES: