The Felsa 415 displayed here originates from the mid 1940ies. The so-called "Bidynator" caliber belongs to the first familiy (here the version with center second, which debuted in 1944) of selfwindig wristwatch movements, on which the rotor winds the mainspring in both directions. This technology was revolutionary and since it was patended, caused lots of headaches for the competitors of Felsa to develop different selfwinding mechanisms.
The movement is decorated with Geneva stripes on the top selfwindig plate, which gives it a very nice look.
The flat rotor with almost the entire mass attached onto an outer lead ring, allowed a very large movement, which had to be flattened only on its outest side.
It allowed the usage of a large balance and large mainspring and very good precision results.
The selfwinding mechanism has got a rocking bar changer mechanism, which drives, according to the direction of the rotor one of both transmission gears. The very long rocking bar leads to a very short ineffective angle of a direction-changing rotor.
On top of the mainspring barrel, there's a clutch with two concentric gears. One is driven by the handwinding mechanism, the other one by the selfwinding mechanism. It's purpose is to detach the selfwinding mechanism when the movement is would by hand.
The Felsa 415 was a bit canny with jewel bearings, only the escapement and second wheel were beared in two jewels, the rest of the timing gears have only got jewels on the dial side, while they're beared in metal bushings on the top plate. And additionally, no single gear of the selfwindig mechanism (except the rotor) is beared in synthetic rubies.
The gold toned screw balance runs in two shock protections, one is the (at that time absolutely new) Incabloc, the other one is unknown. The hairspring can be regulated by a long regulator arm, and, as often seen by selfs, the pallets of the escapement are made of a transparent material.
Of course, this movement uses a yoke winding system on the dial side.