CITIZEN NH9134-83X MECHANICAL MEN WATCH
NH9134-83X
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- 3 Years Warranty
The Citizen NH9134-83X is an open heart — and that one feature is the whole point. A cutaway in the dial exposes the balance wheel beating away underneath, so you watch the mechanism working from the front, not just through the back. Most mechanical watches hide their movement entirely. This one puts it on the dial.
The setting is deliberately traditional so the cutaway does the talking: a green dial with Roman numeral markers, in a two-tone 40mm case at 10.7mm thick. Green with gold accents is a naturally warm pairing, and the Roman numerals keep it classical rather than technical.
Inside is Citizen's Calibre 8229 — 21 jewels, 21,600 vibrations per hour, with roughly 40 hours of power reserve. It is protected by sapphire crystal on the front and a glass exhibition caseback at the rear, so the movement is visible from both sides. Water resistant to 50 metres, on a bracelet with a fold-over push-button clasp.
At a Glance
- BrandCitizen
- CollectionMechanical Open Heart
- MovementCalibre 8229 Automatic
- Case Size40mm
- Thickness10.7mm
- Case FinishTwo-Tone Steel & Gold
- DialGreen, Open Heart
- MarkersRoman Numerals
- GlassSapphire (Top)
- CasebackExhibition (Glass)
- Power ReserveApprox. 40 Hours
- Water Resistance50m (5 BAR)
Why You'll Love It
- The open heart is genuinely uncommon at this price. A cutaway showing the balance wheel is normally a feature of watches costing several times as much — here it is the centrepiece of the dial.
- You see the movement from both sides. Sapphire on the front over the open-heart aperture, and a glass caseback at the rear showing the full calibre and rotor. Most watches offer one or the other.
- Watching the balance wheel oscillate is the most direct answer to "why buy mechanical instead of quartz" — it is the part of the movement that actually keeps time, moving several times a second, in the open.
- Green with two-tone gold is a warm, classical pairing that reads dressier than a steel sports watch without tipping into formal.
- Roman numerals rather than batons keep the dial traditional, which is the right choice against a technical feature like an exposed balance — the two balance each other.
- Sapphire crystal resists the everyday scratches that haze mineral glass within a few years, so the dial stays clear and the open heart stays worth looking at.
- At 40mm and 10.7mm this is a moderate, wearable size that fits under a cuff — many open-heart watches are considerably larger to make room for the aperture.
- No battery, ever. The movement is wound by the motion of your wrist, so there is nothing to replace and no service appointment to remember.
Perfect For
- Mechanical Watch Enthusiasts
- Open Heart Collectors
- Green Dial Collectors
- Two-Tone Watch Fans
- Office & Formal
- First Automatic Watch
- Milestone Gift
- Anniversary Gift
Key Features
- Open-heart dial — a cutaway aperture exposing the balance wheel of the movement, visible from the front of the watch.
- Citizen Calibre 8229 automatic movement — 21-jewel self-winding mechanical movement running at 21,600 vibrations per hour with approximately 40 hours of power reserve. No battery required.
- Green dial with Roman numeral markers — a classical layout framing the open-heart aperture.
- Sapphire crystal — rated 9 on the Mohs hardness scale, over the dial.
- Glass exhibition caseback — a see-through back displaying the full movement and oscillating rotor.
- 40mm two-tone case — 10.7mm thick, in stainless steel with gold-tone elements.
- Two-tone bracelet — matching the case, with a fold-over clasp and push-button closure.
- 50-metre water resistance (5 BAR) — rated for handwashing, rain and brief immersion. Not intended for showering or diving.
Technical Specifications
The Citizen NH9134-83X is a 40mm men's automatic watch from Citizen's Mechanical Open Heart line, powered by Calibre 8229 with 21 jewels, a 21,600 vph frequency and approximately 40 hours of power reserve. The two-tone stainless steel case measures 10.7mm thick with sapphire crystal over the dial and a glass exhibition caseback. The green dial carries Roman numeral markers and an open-heart aperture exposing the balance wheel. Fitted to a matching two-tone bracelet with fold-over push-button clasp and water resistant to 50 metres.
| Model Number | NH9134-83X |
| Case Material | Two-Tone Stainless Steel and Gold-Tone |
| Case Diameter | 40mm |
| Case Thickness | 10.7mm |
| Bezel | Fixed |
| Glass | Sapphire Crystal (Top) |
| Caseback | Exhibition — Mineral Glass |
| Water Resistance | 50 Metres (5 BAR) |
| Colour | Green |
| Aperture | Open Heart (Balance Wheel Visible) |
| Markers | Roman Numerals |
| Display | Hours, Minutes, Seconds |
| Material | Two-Tone Stainless Steel |
| Clasp | Fold-Over with Push-Button Closure |
| Calibre | Citizen 8229 |
| Type | Automatic (Self-Winding) |
| Jewels | 21 |
| Frequency | 21,600 vph (6 beats/sec) |
| Power Reserve | Approx. 40 Hours |
Best Matched With
- Navy Suit
- White Oxford Shirt
- Cream Trousers
- Brown Leather Belt
- Olive Knit Polo
- Tan Loafers
- Camel Overcoat
Frequently Asked Questions
What is an open-heart dial?
A cutaway aperture in the dial that exposes part of the movement underneath — specifically the balance wheel, the component that oscillates back and forth to regulate timekeeping. It moves several times a second and is the part of a mechanical watch that is genuinely alive to look at. Most watches hide it entirely behind the dial.
Can I see the movement from the back as well?
Yes. The caseback is glass, so the full calibre and its oscillating rotor are visible from behind while the balance wheel shows through the dial at the front. Being able to see the movement from both sides is unusual at this price.
Is the case gold or steel?
Two-tone — stainless steel with gold-tone elements across the case and bracelet. It is not solid gold. Two-tone also means it sits comfortably with both silver and gold jewellery, which a single-finish watch cannot.
What does "automatic" mean?
An automatic watch is powered by the natural movement of your wrist. A rotor inside the case winds the mainspring as you wear it, so no battery is needed. If left unworn for about two days it will stop and need resetting — simply wear it again to restart it.
How long does the power reserve last?
Approximately 40 hours when fully wound, so the watch keeps running for close to two days after you take it off. Regular daily wear keeps it continuously wound.
How accurate is a mechanical watch?
Mechanical movements are not as precise as quartz by design — expect to reset the time every week or two. The appeal is the engineering, the absence of a battery, and in this case the ability to watch the balance wheel doing the work.
Does a mechanical watch need servicing?
Yes. Unlike a quartz watch, an automatic has moving parts and lubricants that wear over time. Citizen recommends periodic servicing to keep timekeeping and water resistance within spec. Any City Chain outlet can arrange this — bring your warranty card.
Can I swim with this watch?
No. With 50-metre (5 BAR) water resistance it is rated for handwashing, rain and brief accidental splashes, but it is not intended for swimming, showering or diving. Steam and hot water are particularly hard on seals at this rating.
Will 40mm fit my wrist?
40mm sits in the middle of the modern men's range and suits most wrist sizes from roughly 15cm to 19cm. At 10.7mm thick it is moderate for an automatic — many open-heart watches run larger to make room for the aperture, so this is one of the more wearable examples.
Is the bracelet adjustable?
Yes. The bracelet can be resized by adding or removing links. City Chain offers complimentary bracelet sizing at any outlet — bring your warranty book along for the service.
Is this a good gift?
An open heart makes an unusually good gift because it explains itself. The recipient does not need to know anything about watchmaking to find the moving balance wheel interesting, and the glass caseback gives them a second thing to look at. Paired with sapphire crystal and a two-tone finish, it has the substance to feel like an occasion piece.
What warranty does this watch come with?
The NH9134-83X comes with a 3-year warranty when purchased from City Chain Singapore, an authorised Citizen retailer. Keep your warranty card and proof of purchase — both are required when submitting the watch for service at any City Chain outlet.
Why Buy from City Chain Singapore
- Authorised Retailer 100% genuine Citizen product
- 3-Year Warranty Covered on every purchase
- Free Shipping All orders within Singapore
- Bracelet Adjustment Size it in-store
Extra $15 OFF with min. $200 spend
Use Code: FORYOU15
Extra $30 OFF with min. $400 spend
Use Code: FORYOU30
Caliber No.: 8229
Movement: Automatic (Mechanical)
Jewels: 21 jewels
Frequency: 21,600 vibrations per hour
Case & Build:
Case Size: 40mm
Case Thickness: 10.7mm
Case Material: Stainless Steel
Glass (Top): Sapphire Glass
Glass (Bottom): Mineral Glass
Strap: Stainless Steel Bracelet
Water Resistance: 50 metres
Delivery within Singapore
Order by 11AM
(Mon - Fri for faster processing)
Checkout options may vary depending on order value and eligibility.
• Free Speedpost Domestic Delivery — 1–2 business days
• Free DHL Domestic Delivery — next business day
• Express Delivery — S$30, order by 2PM
• Click & Collect — ready in 2–3 business days. Please wait for the collection confirmation email before visiting the store.
Weekend & Public Holiday Orders
Orders placed after the applicable cut-off time, on weekends, or on public holidays will be processed on the next business day. Delivery will take place on the next available business day based on the selected delivery service.
During peak periods, festive seasons, major launches or sale events, additional processing and delivery time may be required.
For online purchase, you can have bracelet or leather strap adjustments done at any City Chain store. Please bring along your warranty book for the service.
