CITIZEN MECHANICAL NH9138-82A STAINLESS STEEL MEN WATCH
NH9138-82A
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- 3 Years Warranty
The Citizen NH9138-82A is the all-steel reading of Citizen's Mechanical Open Heart line. Case and bracelet are both stainless steel, so the watch reads as one continuous piece from the dial to the clasp, and a silver dial with Roman numeral markers keeps the overall effect formal and understated. Cut into that dial is the open-heart aperture, which leaves the balance wheel visible as it swings back and forth β the detail that gives the line its name and keeps your eye coming back to it.
Driving it is Caliber 8229, a mechanical automatic movement with 21 jewels running at 21,600 vibrations per hour. It winds itself from the motion of your wrist, and can also be wound by hand through the crown when it has been sitting unworn. A transparent caseback shows the rest of the calibre and the winding rotor from the rear, so the movement is on display from both sides β unusual at this level.
The 40mm case measures 10.7mm thick β restrained for an automatic that has to make room for a dial aperture β and is protected by sapphire glass, the hardest crystal material Citizen fits. Citizen specifies 100-metre water resistance, considerably more than most watches of this style offer, and the steel bracelet can be sized in store for a close, comfortable fit.
At a Glance
- BrandCitizen
- CollectionMechanical Open Heart
- MovementCaliber 8229 Automatic
- Case Size40mm
- Thickness10.7mm
- DialSilver with Roman Numerals
- Dial FeatureOpen-Heart Aperture
- CasebackTransparent
- GlassSapphire Glass
- Case & BraceletStainless Steel
- Water Resistance100m
- GenderGent
Why You'll Love It
- The movement is part of the design: The open-heart aperture leaves the balance wheel on show, oscillating steadily on the dial side β the detail that makes a mechanical watch worth looking at rather than just reading.
- Visible from both sides: Sapphire glass over the aperture at the front, a transparent caseback showing the calibre and winding rotor at the rear. Most watches at this level give you one view or the other, not both.
- Winds itself, or by hand when you prefer: Caliber 8229 is self-winding from wrist movement, and the crown lets you wind it manually to get it going after it has been sitting unworn.
- One material, start to finish: Matching stainless steel case and bracelet give the watch a single clean line from the dial to the clasp, and steel takes daily wear in its stride β put it on in the morning and stop thinking about it.
- Dress looks without the fragility: Sapphire glass, a 10.7mm case that slips under a cuff, and 100-metre water resistance β well beyond what this style of watch usually offers β so it handles everyday life rather than only special occasions.
Key Features
- Caliber 8229 Mechanical Automatic β self-winding movement with 21 jewels, beating at 21,600 vibrations per hour.
- Open-Heart Aperture β a dial cut-out exposing the oscillating balance wheel.
- Transparent Caseback β the calibre and winding rotor visible from the rear.
- Hand Winding β the movement can be wound through the crown as well as by wrist motion.
- Silver Dial with Roman Numerals β classic dress-watch legibility.
- 40mm Stainless Steel Case β classic proportions for a men's watch.
- 10.7mm Case Thickness β restrained for an automatic with a dial aperture.
- Sapphire Glass β Citizen's hardest crystal material.
- Stainless Steel Bracelet β matched to the case, adjustable in store.
- 100m Water Resistance β well beyond typical specification for this style of watch.
Technical Specifications
| Model Number | NH9138-82A |
| Collection | Citizen Mechanical Open Heart |
| Case Material | Stainless Steel |
| Case Shape | Round |
| Case Diameter | 40mm |
| Case Thickness | 10.7mm |
| Glass | Sapphire Glass |
| Caseback | Transparent |
| Water Resistance | 100 Metres |
| Dial Colour | Silver |
| Markers | Roman Numerals |
| Dial Feature | Open-Heart Aperture Exposing the Balance Wheel |
| Display Type | Analogue |
| Material | Stainless Steel |
| Adjustment | Adjustable; In-Store Sizing Available |
| Caliber | Citizen 8229 |
| Movement Type | Mechanical Automatic (Self-Winding, Hand-Windable) |
| Jewels | 21 |
| Frequency | 21,600 Vibrations per Hour |
| Functions | Hours, Minutes, Seconds |
| Gender | Gent |
Frequently Asked Questions
Does the NH9138-82A need a battery?
No. It is a mechanical automatic watch powered by Caliber 8229, which winds itself from the natural movement of your wrist. There is no battery and no light charging involved.
What exactly am I looking at through the opening in the dial?
The balance wheel β the component that oscillates back and forth to regulate the watch's timekeeping. Citizen cuts an aperture in the dial so it stays visible while you wear the watch, which is where the Open Heart name comes from.
Can I see the movement from the back as well?
Yes. The caseback is transparent, so the rest of the calibre and the winding rotor are visible from the rear. Between that and the dial aperture, you can watch the movement working from either side.
Can I wind it by hand?
Yes. Caliber 8229 winds automatically from wrist motion and can also be wound through the crown. A manual wind is the quickest way to start it after it has been sitting unworn.
Will it keep running if I don't wear it every day?
Like any automatic watch, it stores energy only while being worn or wound, so it will eventually stop if left unworn. A few turns of the crown or some wrist movement starts it again, and you will need to reset the time.
Can I wear it around water?
Citizen specifies 100 metres of water resistance for this model, which comfortably covers handwashing, rain, splashes and everyday contact with water. Avoid operating the crown while the watch is wet.
How does a 40mm case wear?
40mm is the middle of the range for a men's watch and suits most wrists. At 10.7mm it is notably trim for an automatic with a dial aperture β many open-heart watches run thicker to make room for one. We recommend trying it on at any City Chain store.
Can the steel bracelet be adjusted?
Yes. Links can be removed or added where compatible for a more comfortable fit. City Chain Singapore offers in-store bracelet adjustment β please bring your warranty book with you.
What warranty is included?
This model comes with a 3-year warranty when purchased from City Chain Singapore, an authorised Citizen retailer. Keep your warranty documentation and proof of purchase for any future servicing.
Why Buy from City Chain Singapore
- Authorised Retailer100% genuine Citizen timepieces
- 3-Year WarrantyOfficial warranty coverage
- Free ShippingWithin Singapore
- Bracelet AdjustmentIn-store assistance
Extra $6 OFF with min. $100 spend
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Extra $12 OFF with min. $180 spend
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Caliber No.: 8229
Movement: Mechanical
Strap: Stainless Steel
Water Resistant: 100m
Thickness: 10.7mm
Case Size: 40mm
Case: Stainless Steel
Glass: Sapphire Glass
21 jewels
Automatic
Frequency : 21,600 vph
Gender: Gent
Delivery within Singapore | Order by 11AM
(Checkout options may vary depending on minimum order requirements)
β’ Free Standard Delivery (3 business days)
β’ Free Next Day Delivery
β’ Express Delivery at $30 (order by 2PM)
β’ Click & Collect (ready in 2β3 business days)
Weekend & Public Holiday Orders
Orders placed during this time will be processed on the next business day.
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.
