Martin MA140 Treated 12-54 Light 80/20 Bronze Acoustic Guitar StringsMartin MA140 Treated 12 54 Light 80 20 Bronze Acoustic Guitar Strings Next 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: 167. 3