Martin M-130 Silk & Steel Med-Lt Folk Acoustic Guitar Strings:

 

Martin M-130 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 guitar sound great. The M130 medium light set is made up of selected string gauges, to give you firm feel and response and full, round tone. C. F. Martin is a name synonymous with fine acoustic guitars and guitar strings. Try some on your guitar.

String Diameters:  .0115  .014  .023  .028  .038  .047  inches (Medium Light Gage)

 

From the C. F. Martin Company.