This is Korean built Sigma by Martin acoustic guitar.
Sigma moved their production from Japan to Korea in 1984 - 1994.
It featuresnew strings, a spruce top, mahogany back and sides, rosewood fretboard and an intonated bone saddle. It has the CF martin logo inside the soundhole.
PLays great, sounds wonderful and stays in tune
here's a link to more info on Sigma guitars:
https://en.wikipedia.org/wiki/Sigma_Guitars
swing by and check it out!!