Wind it Friday. It is still running Monday.

There is no rotor in this watch. You wind it with the crown, and the mainspring runs it down over the following days. That is not a cost saving. Hamilton sells automatic Khaki Fields at similar prices. It is a choice, and it is the choice that makes this the purist’s field watch.

The upside is a thinner case, 9.5mm, and a morning ritual. The downside is that if you forget, it stops. The 80-hour reserve is what makes forgetting survivable.

The H-50 is Hamilton’s hand-wound caliber built on an ETA 2801-2 base, running at 21,600 vibrations per hour on 17 jewels. Hamilton has fitted it with a Nivachron balance spring, which resists magnetism, and tuned it for an 80-hour power reserve. The unmodified base movement is rated at far less.

Eighty hours is Friday evening to Monday evening. A watch wound on Monday morning and worn all week never needs thinking about, and a watch left on the dresser for a weekend is still going when you pick it up.

The case is 38mm across and 47mm lug to lug in brushed stainless steel, with 20mm lugs and a sapphire crystal. Those are the proportions that fit most wrists and slide under a shirt cuff, and they are why this reference is so often recommended as a first proper Swiss watch.

The dial is matte black with two rings of numerals, 1 to 12 outside and 13 to 24 inside, and no date. Hamilton rates it to 50m, which is rain and handwashing, not swimming. Hamilton’s own page traces the Khaki Field line to the field watches the brand supplied to the US military. All figures here are Hamilton’s, not ours.