WWII Vintage US Hamilton Model 23 Military Chronograph Pocket Watch-This rare chronograph Military watch is in very good condition and running well. This is the first of its type, produced in the U.S. It a very dependable timepiece and was used widely used during WWII by navigators as a stopwatch. It is a 19 jewel, 16 size watch adjusted to temperature and 3 positions, this was paired with the US Navy Model IV octant, as well as a couple of other sextants. The Model 23 would have been clipped to the side of the Mark IV octant and a trigger pushed the button on the Model 23 to stop and start the stopwatch. The crystal is very good as is very nice black dial. All functions work as they should and start-stop and reset to zero. The watch is marked inside the back with Keystone/Base Metal and Serial number; 938643. It works and is in very good condition.