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Hamilton Khaki Navy Frogman Auto 41mm Mens Watch Black
Ref. H77455331
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Stepping up in the same colour and case shape
The Frogman name goes back to Hamilton's long-standing work equipping military and naval divers, and this 41mm automatic carries that obligation seriously. The H-10 movement inside is Hamilton's own, with an 80-hour power reserve and a Nivachron balance spring that resists magnetic fields — the kind of detail that matters when a dive computer and boat equipment are nearby. The crown guard, shaped like a bridge over the winding crown, is a deliberate callback to the original Frogman's architecture rather than a styling afterthought. At 41mm the case is measured enough to disappear under a wetsuit sleeve, though 14.95mm of thickness means it sits with some presence on a dressed wrist. The green waved rubber strap is the piece that anchors the whole thing — textured to suggest water in motion, and grippy enough to stay put without a second thought. The power reserve indicator on the dial gives a working diver something genuinely useful: a glance before a session to confirm the movement is running, without having to remember the last wind.
- Reference
- H77455331
- Brand
- Hamilton
- Case size
- 41mm
- Case thickness
- 14.95mm
- Lug width
- 20mm
- Case material
- Stainless steel
- Case shape
- Round
- Dial
- Black
- Crystal
- Sapphire
- Movement
- Automatic
- Calibre
- H-10
- Functions
- Power reserve indicator
- Water resistance
- 300m
- Bracelet / strap
- Rubber strap
- Strap colour
- Green
- Clasp
- Buckle
- Lume
- Super-LumiNova
- Retailer
- Goldsmiths
Additional specifications
- Power reserve
- 80 hours
Manufacturer’s guarantee
Your new watch
Frequently asked questions, and things you should know about this watch
Can I swim with it?
Yes. At 300m it is rated for swimming, snorkelling and recreational diving.
Will the glass scratch?
Unlikely. Sapphire is second only to diamond in hardness and shrugs off everyday marking.
Does it need a battery?
No. It is automatic — the motion of your wrist winds it, and there is no cell to replace.
How long does it run for when it's not worn?
About 80 hours fully wound — enough to sit off the wrist over a weekend and still be running.
What size strap does it take?
20mm. Any strap of that width will fit, and on most modern watches quick-release bars make the swap a two-minute job with no tools.
Is it a men's or women's watch?
Listed as men's.
Cheapest place to buy
Goldsmiths is the only UK retailer we track stocking this reference, so there is nothing to compare it against today.
Who are Goldsmiths?
Goldsmiths has been selling watches in Britain since 1778 and is part of the Watches of Switzerland Group, which is listed on the London Stock Exchange. They are an authorised dealer, so a watch comes with the manufacturer’s own warranty.
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