TMI · NH series
NH38
A no-date NH automatic designed to expose its balance through an open-heart dial.
At a glance
- Type
- Automatic mechanical
- Display / complication
- Time only
- Architecture
- Open-heart, three central hands
- Timebase
- 21,600 vph / 3 Hz
- Power reserve
- More than 41 h
- Movement height
- 5.32 mm
- Jewels
- 24
Reference sources reviewed 7 November 2026. Published specifications, not independent measurements. Versions and complete-watch specifications can differ; fields without a verified figure are omitted or identified.
What distinguishes it
Look beyond the reference.
The dial can reveal the balance without exposing the entire movement. An open-heart aperture and a fully skeletonised movement are different things.
For the enthusiast
Often called Seiko NH38; the supplier reference here is TMI NH38A. Compare NH35 if you need a calendar.