EK1 Wilhelm Deumer early not magnetic , so called “schinkel” form screw back (with clampshell disc)
This piece is a popular type among collectors, as it is perhaps the type with the most graceful form, the so-called schinkel form
Compared to the plain traditional PKZ and LDO marked Deumer crosses, these early pieces are real curiosities and are no longer easy and increasingly rare to find.