I'm not an expert on these, but I think this is a bad one. Wait for more experienced members though.
As far as I know, only 3 companies produced the hollowback badges. They are sometimes referred to as "Hymenn Types" after the Hymenn and Co of Ludenscheid. Schickle and Deumer also made a limited number of them. Unfortunately, the pin set up on yours is not resembling any of the 3 companies. Hymenn's badges featured a lighter wire style pin that was horizontal, and while Deumer did use a heavy pin, their orientation was also horizontal. Schickle badges have thin wire verticals. So, I would have to call this one as no good. Sorry, Duff.
"Much that once was, is lost. For none now live who remember it."
That's why I asked!! Wasn't convinced myself.
Thanks Griff, much appreciated!