Martin M200 Silk & Steel Folk 12-String Guitar Strings Martin's M200, light gauge 12-String Silk & Steel, for an amazing folk sound. Precision made, Silk & Steel guitar strings have an intermediate winding of silk fiber between the steel core and the bronze winding, as well as extra silk windings at the ball end. The silk winding at the ball end reduces stress and wear on bridge parts, and helps creates a soft, folk tone and feel. They are a delight to play and make your 12-string acoustic guitar sound great. Try some Martin M200s on your 12-string. You can't beat price for such quality in 12-string acoustic guitar strings. Diameters: .0115 .014 .023 .028 .038 .047 inches .0115 .014 .010 .014 .018 .028 inches From C. F. Martin Company