This is an antique zither from the late 19th to the early 20th century. This is definitely not from the American Revolution era of the 1770's in the 18th century. The US flags on the color lithograph illustration label with more than 13 stars were not in existence prior to the American Revolution when the Colonists gained freedom from Britain. The stars and stripes became official in 1777 and only had 13 stars. In addition, chromolithography was not widely used in America yet in the 18th century. Your black lacquered zither instrument was manufactured by a German maker, named Menzenhauer and this design was patented in 1894. The estimate is based on actual recent past recorded auction sales of comparables. Retail 'asking prices' can be higher and vary.