Imagen: Tudor, web oficial
The storyWhy this reference matters
Tudor has been supplying the Marine Nationale since the fifties, but the episode that matters is 1974. That year the French navy took delivery of a batch of Submariner reference 7016 engraved "M.N. 74" on the case back, carrying a change the navy had asked for itself: square markers and angular hands, for legibility underwater. Those hands are the ones everybody now calls snowflake. They exist because some French divers complained they could not read the dial.
The FXD arrived in 2021, developed with the combat swimmers of Commando Hubert, the French navy's underwater assault unit. Two demands shaped it. The first: no spring bars. The lug bars are machined from the same block of titanium as the case, so there is nothing that can give way and the strap has to be threaded through. Hence the name, FXD, for fixed lugs.
The second demand explains the bezel. These swimmers navigate submerged in straight legs, holding a compass bearing for a set number of minutes, and they cannot surface to check where they are. So the 60-minute scale runs the other way, counting down, and the bezel turns in both directions across 120 clicks: line the leg time up with the minute hand and, when it reaches the triangle, the team changes heading. They work between ten and thirty metres, which makes 200 of water resistance more than generous.
SpecificationsThe numbers, in one table
| Brand | Tudor |
|---|---|
| Family | Pelagos |
| Reference | M25707B-0001 |
| Years made | desde 2021 |
| Calibre | Tudor MT5602 |
| Movement | Automático |
| Frequency | 28.800 alt/h (4 Hz) |
| Power reserve | 70 horas |
| Jewels | 25 |
| Diameter | 42 mm |
| Thickness | 12.75 mm |
| Lug to lug | 52 mm |
| Lug width | 22 mm |
| Case | Titanio |
| Crystal | Zafiro con tratamiento antirreflejos |
| Water resistance | 200 m |
IdentificationHow to tell it apart
Forty-two millimetres of titanium, no date, a matte blue dial with the markers carried right out to the edge of the crystal — there is no raised chapter ring — snowflake hands, and a blue ceramic bezel insert whose numerals grow anticlockwise. The lug bars are fixed: no bracelet will fit, only 22 mm pass-through straps. If the watch has removable spring bars, it is not an FXD.
The case back is steel rather than titanium, screwed down, and carries the Marine Nationale's anchor-and-sailor's-cap crest plus the letters "M.N." followed by two digits: the year of manufacture. Tudor changes those digits annually, so a 2021 example reads M.N.21, then 22, 23, 24. It is the first thing any informed buyer asks for.
There is more than one bezel within the FXD family: the black-dial version uses a conventional unidirectional one, and only the blue Marine Nationale gets the bidirectional countdown. The Alinghi editions are carbon composite, and since 2023 there is a chronograph as well. No confusion is possible with the standard Pelagos, reference 25600TN — that one has a date, a helium valve, 500 metres, a black dial and a titanium bracelet.
CollectingWhat collectors check
The case back engraving is the first thing anyone looks at and the thing they argue about most. M.N.21 case backs were in production for under two months, which makes them the most sought-after in the whole family. Always ask for a photograph of the back with the digits legible before you talk money, and be wary of the listing that skips it and only shows the dial from above.
Titanium does not behave like steel: it marks more readily, and the blasted finish will not come back with a quick polish, because it is not a shine, it is a texture. An FXD described as "as new" with pristine lugs and a chewed-up case elsewhere deserves suspicion. The bezel insert, on the other hand, is ceramic and will not fade in the sun. What it will do is chip if it takes a sharp knock on the edge.
Straps wear out and get replaced: the blue fabric one with the silver thread and the rubber one Tudor supplies are both consumables. What cannot be replaced is the case, so inspect the inside of the fixed lugs and the chamfers the strap passes over, which is exactly where the cuts and burrs of a heavy-handed strap change show up. And check the bezel turns both ways with clean clicks.
Common questionsWhat people ask us about this reference
What does FXD mean on the Tudor Pelagos?
It comes from the fixed lugs. The bars are machined out of the same block of titanium as the case, so there are no spring bars to fail and the strap threads through.
Why does the Pelagos FXD bezel turn in both directions?
Because it is not timing a dive, it is timing legs of a swim. The scale runs backwards, counting down, and combat swimmers use it to change heading on the exact minute.
Only 200 metres on a military watch?
Combat swimmers almost always work between ten and thirty metres. The specification was written for that job: what they asked for was toughness, comfort and nothing that would snag, not depth.
What is the M.N.21 engraving on the case back?
It stands for Marine Nationale 2021, the year of manufacture. Tudor changes those two digits every year, and M.N.21 is the most sought-after because it was in production for less than two months.
Keep readingWhere to go from here
Close relativesThe ones it gets confused with
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