Martin Acoustic MA540 Treated 92/8 Phosphor Bronze Light 12-54 Guitar Strings, 3 PacksNext generation Martin Authentic Acoustic Lifespan 2. 0 strings are engineered using a new, patented anti corrosion treatment only available from Martin. It protects the core and wrap wire to prevent corrosion without compromising tone or feel. Gauge: Light E: . 012 B: . 016 G: . 025 D: . 032 A: . 042 E: . 054 Tension: 168. 5