Martin's patented Lifespan 2.0 treatment protects core and winding for strings that sound better longer. The next generation Lifespan 2.0 strings are engineered using a patented technology only available from Martin, 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. 80/20 Bronze - Medium .013 .017 .026w .035w .045w .056w