Not a rare cap by any means but this one is maker marked and has a date stamp on the underside of the sweat band for 1935.
The cap sports a post 1936 pattern eagle and a velvet cap band. The colour of the crown is much more of a prussian blue found on Imperial caps and the piping a darker shade of carmine than usually found on the fire police caps.
The makers mark under the celluloid states "Herman Schellhorn, Feuerwehrausrustungen (fire dept equipment).
I like the jaunty angle of it ..... or is that just me ?