This set appears to be quite early, perhaps 1840s-50s, and almost surely by Seidel, the best and the most prolific maker of tuners like this in the 19th-century. The fact that the roller spacing is 1-3/8” / 3-3/4”  indicates their having been made before the 1-5/16 / 23-5/8 spacing was standardized, though the spacing of the screw-mounting holes in the back plates is a perfect match for later ones found on Martin guitars. The condition of the gears and worms is near-miraculous, showing no wear, indicating use with gut strings and very little of it. The buttons are also of an earlier style being oval rather than round, and are of beautiful polished bone. The rollers, four of which are present, are also of bone. This is an eminently restorable set, needing only a few rollers to make an early Martin guitar complete. $995