Martin MSP7200-Kit1 SP Lifespan 92/8 Phosphor Bronze Acoustic Guitar Strings, Medium, 13-56, 4 Pack Treated with Martin's Clear tone proprietary technology for a longer lifespan than regular strings Designed to repel the oils and dirt that can deaden strings 92/8 phosphor bronze provides a classically expressive tone Gauge (medium): .013, .017, .026, .035, .045, .056 Includes: 4 Packs of Medium strings & ChromaCast 4 Pick Sampler & string widener