Martin M170 80/20 Bronze Extra Light 3-Pack Acoustic Guitar Strings Bronze alloy for brilliance and long life Studio-quality performance The bronze winding is ideally suited for making strings that have deep, rich basses and clear, bright trebles Gauges: 10-14-23-30-39-47 Martin M170 80/20 Bronze Round Wound Extra Light Acoustic Guitar Strings employ a composition alloy to give brilliance, clarity, and longevity of sound The bronze winding is ideally suited for making strings that have deep, rich basses and clear, bright trebles