A friend collector stayed a little bit more on our GTG place some weeks back and ...
A seller, that arrived late, had a Zenith Respirator NOS to sell and he, of course, grabbed.
To mitigate my regrets he let me to take some pics of his new catch.
It's a Zenith Respirator Luxe AF/P (High frequency / Precision) with the weekdays in German.
About this name, Respirator, it comes from the French "respirateur" and is based on the way this case is built.
There is a large gasket between the glass and the case that "breathes", meaning that as much water pressure increases the case is compressed, increasing the water resistance. It's a 70's design and this gasket, made with 70's rubber, has a strong trend to melt. I already saw some of those Respirators with a major inside damage caused by the melting of the rubber.
There are Respirators, marked with a "X" on the dial, that do not "breathes", meaning that they are Respirators only by the name.
Let's see some pictures:
1) The square/rectangular case is around 37-38 mm. Nice size.