Based on Guild's published serial number records, an M-20 with serial number 15857 was most likely manufactured in
1961. The serial number falls within the 1961 production range of 14714-18419.
If the guitar is original, a 1961 Guild M-20 is a desirable early Hoboken-era instrument. Characteristics you would typically expect include:
Solid mahogany top, back, and sides
Small concert-size body (approximately 13 3/4")
Brazilian rosewood fingerboard and bridge (on many examples from this era)
Made in the Hoboken, New Jersey factory Lightweight construction with a warm, woody tone Popularized decades later by singer-songwriter Nick Drake The value depends heavily on originality and condition