It is a Siemens alarm bell with a dual "fail safe" (Sicherheitsschaltung) circuit. I'm not sure exactly how it works, but it rings loudly on 12VAC. The gongs are the old cowbell shape common on European alarm bells from the WWII era and earlier, but unlike a dull-sounding U.S. Navy cowbell alarm, this has a nice, low pitch with a long resonance. I don't know how old this is. I'll make a sound recording later.
The label translates to "alternating current alarm bell with fail-safe circuit" and the red thing is a cigar lighter to show the size of this thing. At the top of the contact board is a jumper (has two screws and rounded sides) that can be moved to the two holes below it. Perhaps one of our German board members knows about these bells.



