The TMI NH34 is an automatic GMT movement with a central 24-hour hand, date, 24 jewels, hacking seconds and manual winding. TMI lists it at 21,600 vibrations per hour (3Hz), with a movement height of 5.32mm. It is part of the same NH3 family as the NH35, but adds the dedicated GMT hand and second-time-zone setting function.
This guide uses current Time Module (TMI) technical documents and live Watchdives product data checked on September 29, 2026. It separates movement-level specifications from features that belong to the finished watch.
NH34 Specifications at a Glance
Primary technical source: TMI NH Series product page and the official NH34 technical guide.
| Specification | NH34 reference |
|---|---|
| Type | Automatic mechanical GMT |
| GMT display | Central 24-hour hand |
| Frequency | 21,600 vibrations per hour / 3Hz |
| Jewels | 24 |
| Movement height | 5.32mm |
| Running time | More than 41 hours after full winding in TMI's technical guide |
| Factory accuracy reference | -20 to +40 seconds per day under TMI's stated test condition |
| Functions | Hour, minute, seconds, date, GMT / 24-hour hand |
| Winding | Automatic + manual winding |
| Hacking | Yes, stop-second device |
How Does the NH34 GMT Function Work?
TMI's NH34 operation manual shows that the first crown click controls both the quick-set date and the 24-hour hand: turning one direction sets the date, while the other direction sets the 24-hour hand. Pulling the crown to the second click sets the main hour and minute hands.
This means the NH34 lets you adjust the GMT / 24-hour hand independently from the normal local hour and minute hands. Watch enthusiasts often call this type of layout an “office GMT” or “caller GMT”. Those are informal market terms rather than TMI certification labels.
How to Set an NH34 GMT Watch
Follow the exact watch instructions for crown threading and bezel use, but the TMI movement sequence is:
- Set the main time: pull the crown to the second click and turn it to set the hour and minute hands.
- Set the date: use the first crown click in the direction specified by TMI.
- Set the GMT hand: at the same first click, turn the crown in the opposite direction to position the 24-hour hand.
- Return the crown to normal: secure a screw-down crown according to the finished watch instructions.
TMI specifically warns not to quick-set the date between approximately 9:00 PM and 4:00 AM because the calendar mechanism may be engaged during that period.
NH34 vs NH35: What Actually Changes?
| Feature | NH34 | NH35 |
|---|---|---|
| Time display | Hour, minute, seconds + 24-hour GMT hand | Hour, minute, seconds |
| Date | Yes | Yes |
| Frequency | 21,600 vph / 3Hz | 21,600 vph / 3Hz |
| Jewels | 24 | 24 |
| Movement height | 5.32mm | 5.32mm |
| GMT capability | Yes, central 24-hour hand | No |
The practical difference is the GMT complication and the extra hand stack / dial requirements. A shared NH-series architecture does not mean an NH34 can simply replace an NH35 in every case without checking dial, hand, stem and case compatibility.
NH34 Accuracy and Power Reserve
TMI's technical guide gives an isochronism / accuracy reference of -20 to +40 seconds per day under its stated test condition and a running time of more than 41 hours after full winding.
These are movement-level technical references, not a promise that every finished watch will run at one exact daily rate. Regulation, position, temperature, winding state and finished-watch assembly can affect real wrist performance.
How Much Winding Does the NH34 Need?
TMI's current technical guide says a movement can be fully wound by turning the crown a minimum of 55 times. The same documentation also gives winding-machine reference conditions.
That number belongs to the NH34 technical procedure; it should not be copied to unrelated mechanical movements. For normal ownership, follow the instructions supplied with the exact watch and do not force the crown.
Three Current NH34 GMT Watches at Watchdives
The models below had at least one purchasable variant when checked on September 29, 2026.
| Model | Current listed price* | Case / fit | Bezel / water resistance | Why compare it? |
|---|---|---|---|---|
| Watchdives WD0014 | $219 | 41.5mm / 48mm L2L / 12.71mm thick | 24-click bidirectional aluminum GMT bezel / tested 100m | Larger vintage-style NH34 GMT |
| Watchdives WD16760 V2 | From $229 | 40mm bezel / 48mm L2L / 12.5mm thick | 24-click bidirectional ceramic GMT bezel / 300m listing | Higher stated water resistance and multiple bezel/dial configurations |
| San Martin SN005 | From $401.80 | 40mm / 48.57mm L2L / 13mm thick | 24-click bidirectional luminous sapphire GMT bezel / 200m listing | Same NH34 movement with a different finishing and bracelet package |
*Listed USD prices refer to purchasable variants observed on September 29, 2026 and exclude shipping, taxes, duties and checkout-specific promotions.
The same movement does not make these watches interchangeable. Case size, bezel material, water resistance, clasp design, dial and price all belong to the finished watch rather than the NH34 itself.
Is the NH34 a “True GMT”?
“True GMT,” “traveler GMT” and “caller GMT” are informal market terms that can be used inconsistently. The more precise description is how the hands actually adjust.
In the TMI NH34 operating system, the 24-hour GMT hand is independently adjusted at the first crown position, while the main local hour and minute hands are set together at the second position. That is why the NH34 is commonly described as a caller / office GMT rather than a jumping-local-hour travel GMT.
Who Is the NH34 Best Suited For?
The NH34 makes sense when you want:
- an affordable automatic GMT architecture;
- a familiar 3Hz NH-series movement platform;
- a date display plus a second-time-zone hand;
- manual winding and hacking seconds;
- a GMT watch where independently setting the 24-hour hand suits your use.
If you mainly travel and want the local 12-hour hand to jump independently without stopping the movement, verify that function on the exact movement before buying; the NH34 does not use that setting architecture.
Frequently Asked Questions
Is the NH34 automatic?
Yes. TMI specifies both automatic and manual winding.
How many jewels does the NH34 have?
TMI lists 24 jewels.
What is the NH34 power reserve?
TMI's current technical guide states more than 41 hours after full winding under its reference condition.
What is the NH34 accuracy specification?
TMI publishes a -20 to +40 seconds-per-day reference under the test condition in its technical guide. Real finished-watch performance can differ.
Does the NH34 hack?
Yes. TMI lists a stop-second device.
Can I replace an NH35 with an NH34?
Do not assume direct compatibility just because both belong to the NH3 family and share the same listed movement height. The GMT hand stack, dial opening, hand clearance and case design must be checked.
Where can I compare current NH34 watches?
Browse our GMT Watches collection or the GMT Watches Under $300 guide.
TMI technical documents and Watchdives product listings checked September 29, 2026.
