Dynotron ETA ESA 9154 is the electronically controlled balance wheel movement, more precisely, this is a mechanical watch which, instead of a winding spring has an electric solenoid assembly that drives the balance wheel.
The watch was manufactured in the mid-70s, works accurately and precisely, case is thick and massive, all is made of stainless steel.
It is interesting to say that the battery cover is calibrated with numbers from 1 to 12. These numbers represent the months of the year, when you replace the battery put the number of the month in the year in the direction of the small triangle on back case cover and so you know in which month the battery was replaced.
A beautiful watch.