The dial and chapter ring are in outstanding condition.
The watch is fitted with the 21 jewel automatic Hamilton calibre 64A, which was just serviced by my watchmaker and is keeping excellent time.
It looks nice but it is not original and Hamilton did not use such "paint on brass" dials for the 992b.
The Hamilton 992B regulator is adjusted not with a simple "F - S" lever, but with a spring loaded micrometer screw that adjusts the regulator far more precisely.
The case reference of this unusual model is 64040-3.
According to the warranty and inner case markings the watch was manufactured in 1965 and sold in 1966 The watch features a satin silver dial with black inner rotating chapter ring.
Movement size: 16, 1.700 inches, 43.18 mm diameter Approximate watch size (depends on case): 2 inch (5cm) diameter, weight 90g Jewels (gemstone bearings): 21, friction set, all upper jewel settings are gold Rate: 2.5Hz, 5 beats per second, 18000 bph (beats per hour) The watch runs about 52 hours when fully wound Balance wheel: Aurium, a monometallic beryllium-silver-nickel alloy, Aurium is a Hamilton marketing term (trademarked in April 1940 by Hamilton), the exact composition of the alloy was kept secret. Hair spring material: Elinvar-Extra Adjustement: temperature, isochronism and 6 positions Position adjustment refers to the mechanical design of the balance wheel and the hairspring.The watch comes on a choice of black or brown padded leather strap and will be sold with the original box and warranty papers. The Hamilton grade 992B is a high quality antique mechanical pocket watch.Adjustment for isochronism means that the watch runs with the same rate independent of whether the watch if fully wound or almost unwound.Hamilton had in the 1920's a sales and marketing brochure called the Timekeeper and it had a chapter explaining those adjustments: hamilton_adjustments.pdf, 238794 bytes Melamine resin (melamine formaldehyde) was one of the first widely used plastics.