The chinese ZSE was part of the first incarnation of the "First National Standard Movement", the first standardized mens' watch movement. It was made between 1972 and 1974, before it was superseded by the million-seller ZSH series.
The construction is very traditional and easy serviceable - the large four-leg ring balance contains a thick and rugged (hard to break accidentially) hairspring, which is connected to a moveable hairspring stud and whose effective length can be regulated directly on the hairspring key. The balance beats with 21600 A/h and is shock proctected. The shock protection system is made in China and its springs were available in many different shapes, starting from an Incabloc-like type to a "four leaf clover". On this specimen, a heart-like spring was used.
On the dial side, there are no surprise and of course, this movement uses a yoke winding system.
This movement was kindly donated by Klaus Brunnemer. Thank you very much!