Marathon Military Automatic Tritium General Purpose GPM Watch: 24J NH35 Movement

I’ve personally worn this type of watch for over 6 months and rate it highly up there with other automatic watches costing many times more.  It actually gets more wrist time than my Rolex Air King (ref. 5500) which is about the same size.

Each watch has a laser engraved back featuring government required nomenclature with a unique serial number.  The serial number is also repeated on the box the watch comes in.

The new GPM uses a Marathon Japanese made “Dual Winding Movement” (DWM) by SII, Caliber NH35A, and can be wound both by manually winding the crown or by use of the automatic self-winding rotor (transferred from the energy caused from the movement of the wrist). With our new watch winding system, the user will notice that there is an emission of a mechanical noise and a sensation of the rotor oscillating; reassuring the user that the automatic winding system is performing commendably. Once wound, the GPM will run for approximately 41 hours without the need to be wound again. Thanks to the DWM, wearing the watch re-energizes the movement to run continuously for 41 hours. The new movement has 24 jewels (friction reducing rubies), and comes in at a beat rate of 21,600 beats (ticks) per hour, providing a smooth sweep of the central second hand and high accuracy tolerances.

The caliber NH35 is a hand-windable, hacking upgrade from the caliber NH25. It is one of the world’s most popular automatic movements.

As the GPM is a field watch, Marathon was able to make the weight as low as 30 grams (without strap) due to the fiber shell case, which does not sacrifice quality or durability, while keeping weight low. Applied on the dial, minute, and hour hands are self-contained Tritium gas-filled tubes which ensure a constant glow for maximum low-light visibility. Tritium is a trusted source of illumination for military equipment, from watches to aeronautical displays, firearm sights, and binoculars. Tritium tubes glow on their own without the need for charging by an external light source, and will not fade in brightness making it an ideal configuration for nighttime or low light operation. The GPM is water resistant to 3ATM (30 meters/100 feet), making sure that it will not yield to the elements.

Included with the new GPM is a one-piece nylon military strap which is made in accordance with MIL-S-46383B Type II and provides comfort and durability while remaining lightweight. Also available from Marathon are extra nylon straps in various colors to personalize your GPM.  Try a Sage green or black strap to add some variation.