This guitar made before serial numbers were instituted but "3/92", for March 1892, is written in pencil on the underside of the top near the soundhole.
The guitar has three-strut fan bracing typical of the less expensive models Martin offered during this period.
All Martin guitars from the period have back and sides of Brazialian rosewood and an red spruce top, prbably from West Virginia. Style 20 is defined by the use of red and green herringbone for the sound hole ring and the backstripe. The edge purfling are simple black and white lines and the binding is a thin strip of rosewood.
The tuners (likely made by Seidel in Germany) and have bone buttons.
The fingerboard dots are not original and were added a later date.
Photos courtesy of Folkway Music.