Martin 12-54 SP Phoshor SP

The Martin MA540 SP Phosphor Bronze strings are light gauge acoustic guitar strings with gauges of 12-16-25-32-42-54. They are made with a high-quality steel core wire that is wrapped with a phosphor bronze alloy, which gives them a warm and balanced tone with enhanced clarity and projection. The SP designation in the name stands for "Specialty Polymer," which refers to the proprietary coating that is applied to the strings to extend their lifespan and protect them against corrosion and wear.