Gauges 13-17-26-35-45-56.

Rich tone should last as long as the inspiration does. Built on Martin's durable SP core wire, Martin SP Lifespan strings are the next level in studio and stage performance. Now with a more advanced proprietary treatment from America' legendary guitar builder, SP Lifespan strings repel dirt, grit and other environmental elements that can quickly alter the sound of your strings. All six strings are treated to ensure a longer life. Martin developed a new and advanced method to treat strings, resulting in a process that ensures both the core and wrap are protected from corrosion. The molecular level treatment adds almost no mass to the string, will not flake or peel, and does not alter the vibration pattern like some string coatings can. The high-tensile strength SP core wire resists breakage and holds tunings longer “ a perfect match to the treatment in creating a long life string. SP Lifespans are designed to last longer and sound better so you can play on.