Made with bronzed steel core wire and bronze wrap wire these light gauge guitar strings by CF Martin stand the test of time. The pure singing tone offers quality sound that is appropriate for every day play at any skill level. These traditional strings meet strict requirements for rich longevity of use. Long Life The core and wire wrap meet strict requirements to ensure long term use – even if you play every day. Studio-Quality Performance While appropriate for any skill level these high-quality strings withstand the wear of daily use to produce consistent studio-quality performances.