Answer first: The Seiko NH34 is a genuine Japanese automatic movement with a GMT complication: a fourth, 24-hour hand that is set independently of the main time, so the watch shows two time zones at once. Released in 2022, it brought a genuinely functional automatic GMT down to the sub-A$400 price band, territory that belonged to expensive Swiss watches for decades. If you want a mechanical watch that actually tracks a second time zone, this is the calibre to look for.
TL;DR
- NH34 = Seiko's automatic GMT, released in 2022, built on the NH35 architecture.
- It is a caller GMT: the 24-hour hand adjusts independently through its own crown position, so the second time zone is real, not decorative.
- 24 jewels, 21,600 vibrations per hour, more than 41 hours of power reserve, hacking and hand-winding, all from the manufacturer's own specification sheet.
- Found in Rosevari Watches GMT builds under sapphire crystal.
Caller, flyer, fake: the three kinds of "GMT"
The word GMT gets used for three very different mechanisms, and knowing which one you are holding decides how useful the watch is.
- Fake or decorative GMT: a fourth hand that is fixed or slaved to the main movement. It tracks nothing. Common on cheap fashion watches.
- Caller GMT (office GMT): the 24-hour hand is genuinely independent. You point it at a second time zone and it holds that zone while the main hands keep local time. This is the NH34.
- Flyer GMT (traveller GMT): the main local hour hand is the one that jumps independently, in one-hour steps, which suits frequent flyers resetting local time the moment they land. This layout lives almost entirely in Swiss watches costing many times more.
The technical reference Caliber Corner documents the NH34's crown functions plainly: "1 (pulled out one click): Clockwise = GMT hand / Counterclockwise = Date setting", with the main time set at the second click. The hand you move independently is the 24-hour hand, which makes the NH34 a caller GMT, and a genuinely functional one. Nothing about its second time zone is for show. For the wider context on how mods work, start with What is a Seiko mod?.
The NH34 in plain terms
Seiko Instruments builds the NH34 on the same reliable NH35 base that powers most of the mod world, then adds the 24-hour works. Caliber Corner describes it as "an automatic movement based on the Seiko branded 4R34", the calibre Seiko fits to its own GMT models. So you inherit everything good about the NH35: hacking seconds, hand-winding and 24 jewels, plus the second-time-zone complication.
The manufacturer's specification sheet states the numbers without fuss: 21,600 vibrations per hour, a running duration of "more than 41 hours" on a full wind, a stated tolerance of "-20 ~ +40 seconds / day" at 23 degrees Celsius, and, under additional functions, a "24 hour hand or second time zone". Read the calibre honestly and you get a lot for the money: a real automatic, a real dual-time display, and none of the quartz shortcuts.
How the NH34 compares to the movements around it
| Spec | Seiko NH34 | Seiko NH35 | Decorative-GMT quartz |
|---|---|---|---|
| Type | Automatic (mechanical) | Automatic (mechanical) | Quartz (battery) |
| GMT style | Caller GMT, independent 24-hour hand | No GMT | Fourth hand is cosmetic |
| 24-hour hand | Set on its own at the crown's first click | N/A | Fixed or slaved |
| Beat rate | 21,600 bph | 21,600 bph | N/A |
| Jewels | 24 | 24 | Varies |
| Power reserve | More than 41 hours | ~41 hours | Battery (years) |
| Stated accuracy | -20 / +40 s/day | -20 / +40 s/day | ~±20 s/month |
| Hacking | Yes | Yes | Yes |
| Hand-winding | Yes | Yes | No |
| Best for | Second time zone, travel | Everyday tool watch | Looks only |
How you actually set two time zones
Pull the crown out one click and turn it clockwise: the 24-hour hand moves on its own while the watch keeps running (turning the other way sets the date). Pull it out two clicks and the seconds hand stops, the hacking, while you set the main time. The everyday setup is main hands on local time and the 24-hour hand on home time, or on whichever second zone you live against: a head office overseas, family in another country, a market that opens while you sleep.
One honest caveat for frequent flyers: when you land somewhere new, you re-set the time the normal way rather than jumping the local hour hand on its own, because that independent-local-hand trick is the flyer-GMT layout the NH34 does not have. At this price it is a fair trade, and for the far more common use, keeping an eye on one other time zone from home, the caller layout is exactly what you would use anyway.
Reading the bezel: your third time zone
A GMT-style watch has a hidden bonus. With the main hands on local time and the 24-hour hand on home, a rotating 24-hour bezel lets you track a third zone by turning the bezel until the GMT hand lines up with the offset. That is three time zones from one dial, no extra complications. And because the NH34's 24-hour hand re-sets in seconds at the crown, re-pointing your zones is never a chore.
Why the Rosevari Watches GMT builds use it
Our GMT-style watches pair the NH34 with a sapphire crystal, the scratch-resistant material that separates a serious mod from a throwaway one, and a solid case built for daily wear. You get the travel complication, the genuine automatic, and the scratch resistance in one package. It is what makes these builds get looked at twice.
The calibre has earned its place in our order book, too: 15 of the 174 watches we have built to order since launch are NH34 GMT builds (order-book snapshot, 23 August 2026, accessories excluded), and every one of the six colourways runs the same movement.
To be transparent about what the NH34 is not: it is not a flyer GMT, it is not a chronograph, and it is not a quartz set-and-forget. It is a mechanical watch, so it keeps mechanical time (seconds of drift a day, not zero), and it needs winding or wearing to stay running.
Frequently asked questions
Is the Seiko NH34 a true GMT or a caller GMT? It is a caller GMT. The 24-hour hand is genuinely independent, set at the crown's first click, so the second time zone display is real, not decorative. What it does not have is the flyer-GMT layout where the local hour hand jumps on its own; that mechanism lives in far more expensive watches.
Is the NH34 a genuine automatic movement? Yes. It is a Seiko-made mechanical automatic built on the NH35 base, with hacking and hand-winding, not a quartz movement.
How do I set a second time zone on an NH34? Pull the crown out one click and turn clockwise to move the 24-hour hand to your second zone (counterclockwise sets the date). The main time is set with the crown out two clicks. A rotating 24-hour bezel can track a third zone.
How accurate is the NH34? The manufacturer's specification sheet states -20 to +40 seconds per day at 23 degrees Celsius. Most examples settle far tighter, and the movement can be regulated closer. It will never be quartz-perfect, and that is the nature of an automatic.
What is the power reserve on the NH34? More than 41 hours on a full wind, per the manufacturer's specification sheet, so it comfortably runs overnight and through a day off the wrist.
Does Rosevari sell NH34 GMT watches? Yes - our GMT-style builds run the NH34 under sapphire crystal, ship free from Australia, and carry a 1-year AU-based warranty.
Want a real second time zone without the Swiss price? See the GMT collection, or learn the basics in What is a Seiko mod?. Every build is A$399 with free AU shipping, made to order; current build timelines are published on the shipping policy page.
Written by Jordan, founder of Rosevari Watches. I fly with these, so I care that the second time zone actually works the way a traveller needs it to.
Every current NH34 build at A$399: Bruce Wayne · Batman · Pepsi · Coke · Rootbeer · Sprite · Browse all GMT mods