Discovering the Universe of Vintage Zenith: Zenith A 278 Cal 146.
From what I understood, the A 278 is one of the later chronograph using the Cal 146, which is manual winding. We are somewhere in the mid Sixties, if not a bit more.
A good old circa 38 mm case, which wears a tad bigger, a classic dial...
And a screw in case back.
Not bad, this chronograph!