Strings for 12-strings acoustic guitar. Martin’s next generation Lifespan 2.0 strings are engineered using a new, patented technology only available from Martin. This technology was developed to protect the core wire and the wrap wire to prevent corrosion without compromising tone. Authentic Acoustic Lifespan 2.0 strings look better, sound better, and feel better, providing a smooth playing experience that reduces finger drag. Martin Authentic Acoustic Lifespan 2.0 strings offer next generation treatment for long life, great playability and feel, and superior reliability with authentic tone.