Hi there,

I see that there are like a dozen variants of the Zenith El Primero 4021 movement.

4021 B
4021 CN
4021 FN
4021 J1
4021 J2
4021 J3
4021 H
4021 P
4021 SC
4021 SX

Does anyone know what the exact differences are between each of these? They all seem to have the same number of parts and number of jewels.

Is one "version" of the 4021 better / superior to one another?