NH34 GMT Automatic Movement
Complete Your Build
The Seiko NH34 is the only affordable automatic GMT movement available for Seiko modding. Manufactured by TMI (Time Module Inc.), a subsidiary of Seiko Instruments, the NH34 adds a true 24-hour GMT hand to the proven NH35 platform, allowing you to track a second time zone on a GMT bezel. It retains the 21,600 bph frequency, 24 jewels, 41-hour power reserve, hacking seconds, and hand-winding that define the NH family. If you want GMT functionality in a Seiko mod without spending hundreds on a Swiss caliber, this is your movement.
Specifications
| Specification | Detail |
|---|---|
| Caliber | Seiko NH34A |
| Type | Automatic |
| Frequency | 21,600 bph (6 beats per second) |
| Jewels | 24 |
| Power Reserve | 41 hours |
| Hacking | Yes |
| Hand-Winding | Yes |
| Date | Yes |
| GMT | Yes (24-hour hand) |
| Stem Position | 3 o’clock |
| Rotor | Bidirectional |
Compatibility
The NH34 shares the same case mounting dimensions as the NH35 family, so it fits every Nomods case: Royal Oak 37 mm, Royal Oak 41 mm, Petrichor, and Seikonaut. The key difference is the additional GMT hand, which requires a fourth hand to be installed during assembly. Use the NH34 with dials that have 24-hour markings or GMT-style bezels for full GMT functionality, though the movement works with any compatible dial.
Dial sizes: 28.5 mm dials for the Royal Oak 37 mm and Petrichor cases · 30.8 mm dials for the Royal Oak 41 mm and Seikonaut cases
Hands: Requires a four-hand set (hour, minute, seconds, GMT). All Nomods NH-series hands are compatible, plus the additional GMT hand.
What’s Included
- Seiko NH34A movement (fully assembled with rotor)
- Stem
- Movement specification sheet
Why This Movement
The NH34 fills a gap that no other movement in this price range can: affordable automatic GMT. Before TMI released the NH34, getting a GMT complication in a Seiko mod meant either a quartz GMT module or spending several hundred dollars on a Swiss movement. The NH34 puts a true 24-hour GMT hand on the dial at the same price as a standard NH35, making traveler-style builds accessible to anyone. Nomods uses the NH34 in builds where customers want to track two time zones, and it pairs particularly well with GMT bezel inserts for a complete Pepsi, Batman, or Coke aesthetic.
Frequently Asked Questions
How does the GMT function work on the NH34?
The NH34 adds a fourth hand that completes one full rotation every 24 hours. You read it against a 24-hour scale on the bezel or dial to track a second time zone. The local hour hand can be set independently by pulling the crown to the first position and turning it, so you can adjust for time zone changes without losing your GMT reference.
Will the NH34 fit the same cases as the NH35?
Yes. The NH34 has the same external dimensions and mounting points as the NH35, so it drops into every Nomods case — Royal Oak 37 mm, Royal Oak 41 mm, Petrichor, and Seikonaut. The only assembly difference is the extra GMT hand that needs to be installed alongside the standard hour, minute, and seconds hands.
How accurate is the NH34 GMT movement?
The factory specification is ±20 seconds per day, the same as the rest of the NH family. The GMT complication does not affect timekeeping accuracy. As with all NH movements, a watchmaker can regulate the movement for tighter tolerances if desired.
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