Martin MFX700 Phosphor Bronze 12 String Acoustic Guitar Strings , Custom Gauge Gauges: .010/.010 .014/.014 .025/.010 .032/.012 .042/.018 .054/.027 Tensions: 275.3 Advanced thin wire core But don't be fooled by comfort! Just ask tommy Emmanuel, who performs with Martin SP flexible core strings night after night With SP flexible core, you get total flexibility and total control