Seiko HBF003
Ref. HBF003 · In production
- Case42.6 mm
- Thick14.1 mm
- Lug-to-lug49.3 mm
- Water res.300 m
- MovementAutomatic
- CrystalSapphire
Overview
The Seiko HBF003 is a diver watch from the Prospex collection, part of the Marinemaster family. It has a 42.6 mm ceramic case, 14.1 mm thick, 49.3 mm from lug to lug. Inside is a automatic movement (calibre 8L45) with 72 h of power reserve. You also get 300 m water resistance, a sapphire crystal and a bracelet.
Who it suits
- Wrists of roughly 17.1–19.0 cm (6.7–7.5 in), by our Watch Finder sizing guide
- Swimming, snorkelling and diving
Strengths
- Sapphire crystal resists scratches
- Certified to the ISO 6425 diver's standard (300 m)
- Screw-down crown helps keep water out
- 72 h power reserve survives a weekend off the wrist
- Hacks and hand-winds, so it is easy to set
Trade-offs
- Thick at 14.1 mm: harder to slide under a cuff
Written by Watch.co from the published specs below. These are not owner reviews.
Full specifications
Case
| Case diameter | 42.6 mm | seikowatches.com · 23 Oct 2026 |
|---|---|---|
| Thickness | 14.1 mm | seikowatches.com · 23 Oct 2026 |
| Lug-to-lug | 49.3 mm | seikowatches.com · 23 Oct 2026 |
| Case material | Ceramic | seikowatches.com · 23 Oct 2026 |
| Crystal | Sapphire | seikowatches.com · 23 Oct 2026 |
| Anti-reflective coating | Anti-reflective coating on inner surface | seikowatches.com · 23 Oct 2026 |
| Caseback | Screw | seikowatches.com · 23 Oct 2026 |
| Bezel | Unidirectional rotating | seikowatches.com · 23 Oct 2026 |
| Water resistance | 300 m | seikowatches.com · 23 Oct 2026 |
| Screw-down crown | Yes | seikowatches.com · 23 Oct 2026 |
| ISO 6425 diver | Yes | seikowatches.com · 23 Oct 2026 |
| Magnetic resistance | 4,800 A/m | seikowatches.com · 23 Oct 2026 |
Dial
| Luminous material | LumiBrite | seikowatches.com · 23 Oct 2026 |
|---|---|---|
| Date | Date | our classification |
Movement
| Movement type | Automatic | seikowatches.com · 23 Oct 2026 |
|---|---|---|
| Calibre | 8L45 | seikowatches.com · 23 Oct 2026 |
| Made in-house | Yes | seikowatches.com · 23 Oct 2026 |
| Power reserve | 72 h | seikowatches.com · 23 Oct 2026 |
| Hacking seconds | Yes | seikowatches.com · 23 Oct 2026 |
| Hand-winding | Yes | seikowatches.com · 23 Oct 2026 |
Strap / Bracelet
| Bracelet / strap | Bracelet | seikowatches.com · 23 Oct 2026 |
|---|---|---|
| Lug width | 20 mm | seikowatches.com · 23 Oct 2026 |
Other
| Production status | In production | seikowatches.com · 23 Oct 2026 |
|---|---|---|
| Style (our classification) | Diver | our classification |
Specs are summarised in our own words from the brand's product page. Each row links its source and the date we checked it. Fields we haven't verified are left out rather than guessed.
Variants with the same specs
Same case, movement and bracelet or strap; typically a different dial or finish.
More in Marinemaster
Similar alternatives
Picked with Watch Finder's style tags and sizing.
Questions about the Seiko HBF003
How big is the Seiko HBF003?
The case is 42.6 mm wide, 14.1 mm thick and 49.3 mm from lug to lug.
What movement does the Seiko HBF003 use?
It uses the 8L45 calibre, a automatic movement with 72 h of power reserve.
Can I swim with the Seiko HBF003?
Yes. It is rated to 300 m and certified as an ISO 6425 diver.
Does the Seiko HBF003 have a date?
Yes, it shows the date.
Will the Seiko HBF003 fit my wrist?
By our sizing guide it sits best on wrists of about 17.1–19.0 cm (6.7–7.5 in). Use the fit checker on this page to test your own wrist.
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