Jaeger-LeCoultre reference 2400: the T.W.O in One

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This year it has been very clear that one of the strategies used by several watch brands is to offer the same watch in many different versions. Using a lot of different dial- or strap colours for the same reference to make us feel there is a lot of new offers…

I think in todays fashion with the watch as a colourful matching accessory this is a working concept – get your favourite watch in any of your favourite colours!

Only downside is that you need to have several of the same watch…

Another, more traditional way is to offer variation is to have the same watch in different case metals… Still with the same downside, you need to have several of the same watch…

In 1931 the Reverso was first introduced as a sports watch, by reversing the middle part of the case, the wearer could protect the weakest part of the watch – the crystal during horse polo or similar activates.

Jaeger-LeCoultre catalogue – early 1930s

Later, much later, in 1994, the Reverso Duo was introduced, with the manual movement, Calibre 854 in the Grande Taille case – the birth of “Two in One” Reverso – finally there was a way to have two watches in one!

Jaeger-LeCoultre catalogue 1995/1996 – Reverso Duo

Any Reverso Duo owner knows the advantage of having different dials to chose from in the same watch!

But the Reverso Duo was not the first “two in one” watch from Jaeger-LeCoultre!

I do not have the exact year of release, but sometimes late 1930’s, Jaeger-LeCoultre released the reference 2400, the first two in one watch from Le Grande Maison!

Jaeger-LeCoultre reference 2400 – the T.W.O in One

Based on the fact that my reference 2400 have LeCoultre on the dial but no VXN import markings on the movement and a French gold case makes me think this one originates from the time around or before the merge of the two brand logos Jaeger and LeCoultre on watch dials, 1936-1937. Another indication of this is the movement number which aligns with the same period.

So what is the reference 2400 and how is it a two in one watch?

Here is a drawing of the 2400, courtesy of the Jaeger-LeCoultre Heritage Gallery:

Jaeger-LeCoultre drawing – reference 2400

A rectangular Art Deco designed watch. Quite similar to the Reverso in style minus the revisable mid-section.

Case dimensions: 21 x 35 mm excluding the crown and 8.5 mm thick including the raised crystal. The hidden lugs makes the watch wear bigger that dimensions on paper.

Inside is the manual movement, Calibre 438 (11”’LO) based on the Calibre 424 (11”).

Base Calibre 424:

Jaeger-LeCoultre Calibre 424 specification

And the Calibre 438, courtesy of the Jaeger-LeCoultre Heritage Gallery:

Jaeger-LeCoultre Calibre 438 specification

The Calibre 438 were in production between 1940 to 1961 and made in a number of 92.870 movements! All of the movements were not made for the reference 2400…

I have no production numbers of the 2400, but based on observations it must be a rather small number. Google it and you will not find many…

As I have been reporting previously, many different watches used the Calibre 438, several of the them in the U.S. market, like the Sultan and the 390/2406 Assymetric.

My watch is pre-1940 using the Calibre 410 (11LO) same as some of the Reverso and Uniplan from the time.

Uniplan Calibre 410 (11”LO) advertisement from 1936:

LeCoultre Uniplan Calibre 410 (11”LO) – advertisement1936

I suspect if we would be able to look deeper into the Jaeger-LeCoultre archives, it would be possible to confirm this as the original drawing says 11” and a later note added the 424.

Another interesting detail is the added note of discontinued on the drawing – as late as 1963!

OK, so you saw the drawing of the stainless steel version, you saw photo of my rose gold version – how do this make the 2400 a two in one watch?

Here is a scan from an early 1950’s Jaeger-LeCoultre catalogue featuring the reference 2400: “Watch with stainless steel case, supplied with two interchangeable frames (one in 18kt. gold and the other in steel). Rectangular 11”LO movement.

Early 1950s Jaeger-LeCoultre catalogue – reference 2400

Just push the crystal to pop out the stainless steel case out of the frame and then insert the case into the other frame.

T.W.O in One – one 18K gold frame and one stainless steel frame!

Jaeger-LeCoultre reference 2400 – outside frame

In profile the hidden lugs are shown and the bottom of the steel case which hold the movement. If you look close, you see the crystal raised up through the metal frame.

Another detail that can be seen in this photo is the 18K gold Hallmark, the French market eagle head.

Jaeger-LeCoultre reference 2400 – profile

On the wrist the 2400 is very pure, very elegant. The Art Deco design fits this watch perfectly and the hidden lugs is the cherry on the cake which makes it perfect!

Jaeger-LeCoultre reference 2400 – on the wrist

Now, if I only could find me a matching steel frame…

Big thank you to the Jaeger-LeCoultre Heritage Gallery for sharing their archives with us here!

Stay tuned for more T.W.O in One watches!