Tissot, numbers engraved on lug

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Hi,
Does anyone know what purpose the numbers engraved on the back of the lug serve on this Tissot? I tried searching this question but couldn’t find if it has been answered here.
Thanks all. By the way, anyone just watch the Wilder v Fury fight? 😀
 
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It's the case number that's matched to the caseback. It was usually done with snap backs but the practice may have been kept on.
 
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It's the case number that's matched to the caseback. It was usually done with snap backs but the practice may have been kept on.
Silly me. I never even thought to compare it to the caseback. Was it a common practice to have the caseback and cases match exactly? For military purposes? I mean a caseback from a 145.022 Speedmaster for example could be swapped on to many others of that same reference.
 
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Silly me. I never even thought to compare it to the caseback. Was it a common practice to have the caseback and cases match exactly? For military purposes? I mean a caseback from a 145.022 Speedmaster for example could be swapped on to many others of that same reference.

It's the same on all Taubert et Fils and Francois Borgel made cases as well as Longines watches of that period (sorry, don't know the case maker). It has probably to do with preventing parts getting mixed together on production lines and at watchmakers, there is no military connection.
 
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is there any numbers engraved inside the caseback ?
In not sure. I can check when I get back home. Would it be the same numbers again?
 
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What calibre movement is that?
I’m not sure of that either. Would it be on the movement somewhere?
 
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I’m not sure of that either. Would it be on the movement somewhere?

Many Tissot movements (all the way from 17.2s to 21.7 and higher) were identical except for size.
What is the diameter of the movement in millimetres?
 
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Many Tissot movements (all the way from 17.2s to 21.7 and higher) were identical except for size.
What is the diameter of the movement in millimetres?
I’ll check that also when I get back. The case is approx 31mm.
 
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What calibre movement is that?
I’m not sure of that either. Would it be on the movement somewhere?
That looks like a Tissot 27-3. The watch dates to 1940.
 
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Many Tissot movements (all the way from 17.2s to 21.7 and higher) were identical except for size.
What is the diameter of the movement in millimetres?
The movement is 27mm.
 
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is there any numbers engraved inside the caseback ?
No numbers on the inside of the caseback
 
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Ok, so no reference but only the serial number. Thanks
 
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That looks like a Tissot 27-3. The watch dates to 1940.

👍

D= 26.5mm, total dia 27.0mm. Size 12'''