Martin 12-56 SP 80/20 Bluegrass (neM240)

The Martin M240 SP 80/20 Bronze Bluegrass guitar strings are a set of medium gauge strings designed specifically for bluegrass players. The gauges for this set are 12-16-25-35-45-56. They are made with an 80/20 bronze alloy, which provides a bright and well-balanced tone that is ideal for cutting through in a bluegrass ensemble.

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.