Martin SP 7200 Phosphor Bronze Lifespan Coated Medium Acoustic Strings - 2 Pack SP 7200 Phosphor Bronze Lifespan Coated Medium Acoustic Strings - 2 Pack The Martin SP 7200 Phosphor Bronze Lifespan Coated Medium Acoustic Strings - 2 Pack is the perfect answer to the age old question "Should I just get one pack or should I get two?" Martin is here to answer that for us Martin SP Lifespan acoustic guitar strings are treated with Cleartone proprietary technology to bring you the longest possible string life without sacrificing tone or natural feel Recommended for all types of musical styles these strings are designed to repel the oils and dirt that can deaden strings Phosphor Bronze strings are bright, but slightly warmer sound than 80/20 bronze when first put on the guitar and offer consistent tone over time