Martin Authentic Acoustic LifeSpan 2.0 strings are engineered using Martin's own patented technology developed to protect both the wrap wire and core wire of the string. This barrier prevents corrosion and oxidisation which could comprise tone and life. Martin LifeSpan 2.0 strings stay looking, sounding and feeling better for longer than normal strings providing a smooth playing experience. The core is Martin's highest tensile-strength which is then tin-plated for corrosion resistance (including the non-wounds). The cores are then wrapped with Martin's highest quality 92/8 Phosphor Bronze wire which consistently delivers a warm, full and balanced tone.