If you've never seen a disassembled Chronomatic before..

Many here will know the difference between an integrated chronograph (e.g. El Primero) and a piggy back movement, like the Chronomatic (Cal. 11/ 12/ 14/ 15) series.

Essentially, the latter takes a base movement used for a 3-hand watch and bolts a chronograph module on top. This great photo that Abel took of my watch shows the two parts really well- I'd never seen it before

In the case of the Chronomatic movement, the base movement was designed by Buren, which was bought by Hamilton in 1966. You can see the micro-rotor above- very different to the large rotor used on the Calibre 1887 for example.

And the second component is the Chronograph module designed by Dubois-Depraz, who also make the chronograph module for many of TAG Heuer's movements today, including the new Calibre 12 used in the Monaco- an entirely different movement, but with the same name.

Great pic - thanks David and Abel for sharing! Like you, David, I understood the general design but had never seen the two parts separated before. Great stuff!

Here's some more...typically the chronograph module is normally not taken apart completely when servicing. This one is the "economic" version of the Caliber 15, being the Caliber 15.