TUDOR · Black Bay 58 GMT and Black Bay GMT
TUDOR M7939G1A0NRU-0003 vs TUDOR M79830RB-0001
11 published specifications differ between these two, and 2 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 58 GMT, black and burgundyM7939G1A0NRU-0003 | TUDOR Black Bay GMT 41mm, burgundy and blue bezelM79830RB-0001 |
|---|---|---|
| Case | 39mm stainless steel case with polished and satin finishes | 41mm steel case with polished and satin finish |
| Diameter | 39 mm | 41 mm |
| Bezel | 24-hour bidirectional rotatable bezel in stainless steel with black and burgundy anodised aluminium insert | Bidirectional rotatable 48-notch bezel in steel with a 24-hour graduated anodised aluminium disc in matt burgundy and blue |
| Dial | Black, domed, with gilt applied hour markers | Black, domed |
| Crown | Stainless steel screw-down winding crown with the TUDOR rose in relief | Steel screw-down winding crown with the TUDOR rose in relief, with circular satin-brushed steel winding crown tube |
| Bracelet | 5-link stainless steel bracelet with polished and satin finishes | Riveted steel bracelet with polished and satin finish |
| Clasp | TUDOR "T-fit" clasp | Folding clasp with safety catch |
| Calibre | Manufacture Calibre MT5450-U | Manufacture Calibre MT5652 |
| Movement | Self-winding mechanical movement with bidirectional rotor system, integrated GMT function | Self-winding mechanical movement with bidirectional rotor system, built-in architecture |
| Power reserve | 65-hour power reserve | Approximately 70 hours |
| Certification | COSC and METAS certified | COSC |
What is identical
Worth knowing as much as the differences: these are the specifications you cannot use to tell the two apart.
- Water resistance
- Waterproof to 200m (660 ft)
- Crystal
- Domed sapphire crystal
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.
| Thickness | 12.8 mm | not stated |
|---|---|---|
| Lug width | 20 mm | not stated |
| Movement notes | not stated | TUDOR states a five-year transferable guarantee with no registration or periodic maintenance checks required. |
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.
These reach different buyers
41 mm on the M79830RB-0001 against 39 mm on the M7939G1A0NRU-0003. 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.
Different movements to verify and to service
The M7939G1A0NRU-0003 runs the Manufacture Calibre MT5450-U and the M79830RB-0001 the Manufacture Calibre MT5652. Two consequences at intake: the service history that is normal for one calibre is not evidence about the other, and the calibre is the check that catches a movement swapped into the wrong case. Confirm the movement matches the reference rather than assuming it from the dial.
What to check on each
M7939G1A0NRU-0003
- Turn the bezel both ways. This reference uses a bidirectional 24-hour bezel, and a bezel that refuses to turn anticlockwise belongs to a dive reference, not this one.
- Check the colour split on the insert lines up exactly with the 24-hour graduation. A misaligned two-tone insert is immediately obvious and indicates the part has been off.
- Run the GMT hand through a full rotation and confirm it reads correctly against the bezel at both the day and night ends of the scale.
M79830RB-0001
- Grade the bezel disc as anodised aluminium. It fades and dents rather than chipping, so a paler burgundy on a used example is ageing rather than damage.
- Count the bezel through a full revolution against the specified 48 notches and confirm it turns freely both ways, which is correct for a timezone bezel.
- Check the crown tube is the circular satin-brushed steel type specified, since TUDOR calls the tube out separately on this reference.
Sources
- TUDOR official product page for reference M7939G1A0NRU-0003 (Black Bay 58 GMT; 39mm steel case; black and burgundy bezel) - Case: 39mm stainless steel case with polished and satin finishes; Lugs: 20mm lug width; Case thickness: 12.8mm; Waterproofness: waterproof to 200m (660 ft); Bezel: 24-hour bidirectional rotatable bezel in stainless steel with black and burgundy anodised aluminium insert; Dial: black; domed; with gilt applied hour markers; Crystal: domed sapphire crystal; Movement: Manufacture Calibre MT5450-U (COSC and METAS certified); self-winding mechanical movement with bidirectional rotor system; integrated GMT function; Power Reserve: 65-hour power reserve; Winding Crown: stainless steel screw-down winding crown with the TUDOR rose in relief; Bracelet: 5-link stainless steel bracelet with polished and satin finishes with TUDOR T-fit clasp — retrieved 2026-09-22
- TUDOR official product page for reference M79830RB-0001 (Black Bay GMT; 41mm steel; burgundy and blue bezel) - Case: 41mm steel case with polished and satin finish; Waterproofness: Waterproof to 200m (660 ft); Bezel: Bidirectional rotatable 48 notches bezel in steel with 24-hour graduated anodised aluminium disc in matt burgundy and blue; Dial: Black, domed; Crystal: Domed sapphire crystal; Movement: Manufacture Calibre MT5652 (COSC); self-winding mechanical movement with bidirectional rotor system; built-in architecture; Power Reserve: Power reserve of approximately 70 hours; Winding Crown: Steel screw-down winding crown, with the TUDOR rose in relief, with circular satin-brushed steel winding crown tube; Bracelet: Riveted steel bracelet with polished and satin finish with folding clasp and safety catch; Guarantee: Five-year transferable guarantee with no registration or periodic maintenance checks required — retrieved 2026-09-23
Not affiliated with TUDOR. Specifications are read from each manufacturer's own published documentation on the dates shown and may change; the manufacturer's current documentation governs.