From Martin: 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 – the single most important attribute of the guitar strings. Authentic Acoustic Lifespan 2.0 strings look better, sound better, and feel better, providing a smooth playing experience that reduces finger drag. We invested two years developing our next generation Lifespan 2.0 strings to ensure they will sound better, longer than any other extended-life string on the market. Gauges: 12-16-25-32-42-54