TUDOR · Black Bay 58 and Black Bay 58 GMT
TUDOR M7939A1A0NU-0001 vs TUDOR M7939G1A0NRU-0003
5 published specifications differ between these two, and 10 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, 39mm steel on braceletM7939A1A0NU-0001 | TUDOR Black Bay 58 GMT, black and burgundyM7939G1A0NRU-0003 |
|---|---|---|
| Thickness | 11.7 mm | 12.8 mm |
| Bezel | Unidirectional rotatable bezel in stainless steel with anodised aluminium insert | 24-hour bidirectional rotatable bezel in stainless steel with black and burgundy anodised aluminium insert |
| Dial | Matt black, domed, with applied hour markers | Black, domed, with gilt applied hour markers |
| Calibre | Manufacture Calibre MT5400-U | Manufacture Calibre MT5450-U |
| Movement | Self-winding mechanical movement with bidirectional rotor system | Self-winding mechanical movement with bidirectional rotor system, integrated GMT function |
What is identical
Worth knowing as much as the differences: these are the specifications you cannot use to tell the two apart.
- Case
- 39mm stainless steel case with polished and satin finishes
- Diameter
- 39 mm
- Lug width
- 20 mm
- Water resistance
- Waterproof to 200m (660 ft)
- Crystal
- Domed sapphire crystal
- Crown
- Stainless steel screw-down winding crown with the TUDOR rose in relief
- Bracelet
- 5-link stainless steel bracelet with polished and satin finishes
- Clasp
- TUDOR "T-fit" clasp
- Power reserve
- 65-hour power reserve
- Certification
- COSC and METAS certified
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.
Different movements to verify and to service
The M7939A1A0NU-0001 runs the Manufacture Calibre MT5400-U and the M7939G1A0NRU-0003 the Manufacture Calibre MT5450-U. 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
M7939A1A0NU-0001
- Verify the calibre is MT5400-U rather than an earlier MT5402. The Master Chronometer version is a different movement, and the two are easy to conflate in a listing written from memory.
- Inspect the anodised aluminium bezel insert closely. Aluminium marks in a way ceramic does not, and insert condition is one of the larger swings in desirability on this reference.
- Work the five-link bracelet's T-fit clasp through its adjustment range, and check the links for stretch at the pins.
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.
Sources
- TUDOR official product page for reference M7939A1A0NU-0001 (Black Bay 58; 39mm steel case; steel bracelet) - Case: 39mm stainless steel case with polished and satin finishes; Lugs: 20mm lug width; Case thickness: 11.7mm; Waterproofness: waterproof to 200m (660 ft); Bezel: unidirectional rotatable bezel in stainless steel with anodised aluminium insert; Dial: matt black; domed; with applied hour markers; Crystal: domed sapphire crystal; Movement: Manufacture Calibre MT5400-U (COSC and METAS certified); self-winding mechanical movement with bidirectional rotor system; 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; the unidirectional rotatable bezel rotates in one direction only and is deliberately harder to turn when the zero marker is at 12 o'clock to avoid inadvertent rotation — retrieved 2026-09-22
- 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
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.