Sturgill aquired this Ditson-style dreadnaught (modeled after the origional Martins built for Ditson department stores in the 1920s) after becoming a Martin Ambasador. It has mahogany back and sides, adirondack spruce top, is 12 frets to the body, and features a slotted headstock.
In his interview for the Martin Journal of Acoustic Guitars (Vol. 5, January 2016), Sturgil talks about why he chose this particular guitar: "I like a lot of bottom end, because I'm primarily a rythm player and a singer," says Simpson. "I picked up a couple 12-fret older model Dreadnaughts in the stores, and they just felt like more resonant, louder guitars. And then I saw the Ditson in the Martin Museum when I toured the factory and just kind of fell in love with the simplicity of the aesthetic of it. No bells or whistles, just a workhorse. This one's really alive already, I can tell, and I'm excited to hear it in a couple of years. I really would like to meet the luthiers who made it, 'cause it's just an absolute tank. It sounds like a cannon." (https://issuu.com/cfmartin/docs/martinjournal_vol5_jan2016)