Tommy Emmanuel Signature Strings Phosphor Bronze .012 -.054. It isn't just about flexibility; it's about bending the note till it rings true. Martin SP Flexible Core strings have a thin but strong core wire and a thicker wrap wire which allows them to be flexible and easy on the fingers while holding standard tension. SP Flexible Core strings feel soft to the touch, making them ideal for beginners. But don't be fooled by comfort! Just ask Tommy Emmanuel who performs with Martin's SP Flexible Core strings night after night. With SP Flexible Core, you get total flexibility and total control.Gauges: MA540FX Light Tommy Emmanuel 12 16 25 32 42 54 Martin & Co. designs and manufactures the strings themselves! • MFSKU 41Y19MA540FX • UPC 729789558013