Seiko against TUDOR
Seiko SPB453J1 vs TUDOR M79000B-0001
13 published specifications differ between these two, and 1 are identical. Every figure below is what the manufacturer states for that reference; nothing is inferred from the other watch.
What differs
| Specification | TUDOR Black Bay 54, 37mm blue dialM79000B-0001 | |
|---|---|---|
| Case | Stainless steel, 40.0 mm | 37mm stainless steel case with polished and satin finish |
| Diameter | 40 mm | 37 mm |
| Thickness | 13 mm | 11.2 mm |
| Water resistance | 300m / 1000ft diver's | Waterproof to 200m (660 ft) |
| Crystal | Curved sapphire crystal, anti-reflective coating on inner surface | Domed sapphire crystal |
| Bezel | Unidirectional rotating bezel | 60-minute unidirectional bezel in stainless steel with aluminium insert devoid of minute graduations |
| Crown | Screw-down crown | Stainless steel screw-down crown with the TUDOR rose in relief |
| Bracelet | 20 mm between the lugs | 3-link stainless steel bracelet with polished and satin finish |
| Clasp | Three-fold clasp with secure lock, push button release with extender | TUDOR "T-fit" clasp |
| Calibre | 6R55 | Manufacture Calibre MT5400 |
| Movement | Automatic with manual winding | Self-winding mechanical movement with bidirectional rotor system |
| Power reserve | Approximately 72 hours (3 days) | Power reserve of approximately 70 hours |
| Movement notes | Precision stated as +25 to −15 seconds per day. Stop second hand function. LumiBrite on hands, indexes and bezel. Total weight 168.0 g. | Chronometer certified. Note this is the COSC calibre rather than the METAS-certified MT5400-U used elsewhere in the family. |
What is identical
Worth knowing as much as the differences: these are the specifications you cannot use to tell the two apart.
- Lug width
- 20 mm
Stated for one, not the other
These rows cannot be compared, because one maker publishes the figure and the other does not. An empty cell is a gap in the manufacturer's documentation, not a gap in the watch — and not a licence to fill it in from the other column.
| Lug to lug | 46.4 mm | not stated |
|---|---|---|
| Dial | not stated | Blue, domed, with applied hour markers |
| Case back | Screw case back | not stated |
| Jewels | 24 | not stated |
| Certification | not stated | COSC |
What the differences cost you
Each note below follows from the published figures in the tables above — what they mean for intake, for a listing, and for the handover. Nothing here estimates a price or a margin.
You will have to measure one of these
Lug to lug is published for the SPB453J1 but not for the M79000B-0001. It is the figure that actually predicts fit, so measure the M79000B-0001 yourself with callipers and say in the listing that the number is your own measurement, not the maker's.
These reach different buyers
40 mm on the SPB453J1 against 37 mm on the M79000B-0001. Diameter is a poor predictor of how a watch actually sits, but it is the field buyers filter on, so the two land in front of different people. Do not let one listing's photographs or copy stand in for the other.
A visible difference in how they wear
1.8 mm of thickness separates these, with the SPB453J1 the taller at 13 mm. That is the difference between a watch that goes under a cuff and one that catches on it — worth a photograph from the side rather than a number in a table.
Do not describe these the same way
300 metres on the SPB453J1 against 200 on the M79000B-0001. Both are more than daily life asks for, so the number is a listing-accuracy question rather than a practical one: quote each watch its own figure, and remember that neither rating survives an unserviced case by itself.
What to check on each
SPB453J1
- Read the published precision before you time one. Seiko states +25 to −15 seconds per day, so an example gaining twenty seconds daily is inside its own specification and is not a fault to price around.
- Test the clasp extender as well as the clasp. It is a moving part with its own catch, it is used over a wetsuit, and it is the component most likely to have been bent.
- Turn the bezel anticlockwise through a full revolution and confirm it will not move the other way at all. A unidirectional bezel that turns both ways has lost its safety function.
M79000B-0001
- Read the bezel insert carefully: TUDOR states it is devoid of minute graduations. An insert showing minute markings is not the one this reference ships with, and that is a substitution worth understanding before you buy.
- Check which MT5400 is fitted. This reference is specified with the COSC calibre, not the Master Chronometer variant, and conflating the two overstates what you are selling.
- Assess the case for over-polishing. At 37mm the lugs are slim to begin with, and an aggressive refinish shows on this size far sooner than on a larger watch.
Sources
- Seiko official product page for reference SPB453J1 (Prospex Sea, 1965 Heritage Diver's Watch) - Caliber Number: 6R55; Movement Type: Automatic with manual winding; Precision: +25 to -15 seconds per day; Power reserve: Approx. 72 hours(3 days); Jewels: 24; Case Material: Stainless steel; Case Size: Thickness:13.0mm; Diameter:40.0mm; Lug-to-lug:46.4mm; Crystal: Curved sapphire crystal; Crystal Coating: Anti-reflective coating on inner surface; LumiBrite: LumiBrite on hands, index(es) and bezel; Clasp: Three-fold clasp with secure lock , push button release with extender; Distance between lugs: 20; Water Resistance: 300m / 1000ft diver's; Weight: 168.0g; Functions: Stop second hand function; Features: Unidirectional rotating bezel; Screw-down crown; Screw case back — retrieved 2026-09-22
- TUDOR official product page for reference M79000B-0001 (Black Bay 54; 37mm steel case; steel bracelet) - Case: 37mm stainless steel case with polished and satin finish; Lugs: 20mm lug width; Case thickness: 11.2mm; Waterproofness: waterproof to 200m (660 ft); Bezel: 60-minute unidirectional bezel in stainless steel with aluminium insert devoid of minute graduations; Dial: blue; domed; with applied hour markers; Crystal: domed sapphire crystal; Movement: Manufacture Calibre MT5400 (COSC); self-winding mechanical movement with bidirectional rotor system; Power Reserve: power reserve of approximately 70 hours; Winding Crown: stainless steel screw-down crown with the TUDOR rose in relief; Bracelet: 3-link stainless steel bracelet with polished and satin finish with TUDOR T-fit clasp — retrieved 2026-09-22
Not affiliated with Seiko or TUDOR. Specifications are read from each manufacturer's own published documentation on the dates shown and may change; the manufacturer's current documentation governs.