Martin Guitars MM13 Retro Medium

Martin Guitar Retro Medium MM13 - String set for acoustic steel-string guitar
Strings with retro sound in legendary alloy!
The Retro model has Plain strings in steel but the spun ones are made of Martin's classic Monel alloy of Nickel and Copper, just like it was in the 1930s. The alloy is naturally resistant to corrosion which gives strings that hold their tone for a long time.
The strings have a less prominent touch which allows the guitar's natural sound and tone to come through in a fantastic way.

Retro Medium MM13 contains:
E: 013
B: 017
G: 026 Spun
D: 035 Spun
A: 045 Spun
E: 056 The Spun
 
Specifications:
Model: Medium
Spun strings in an alloy of Nickel & Copper
Plain steel strings
Tension 190.9 lbs
Manufacturer's part number MM13