This is a Third Reich-era Mercedes Benz Logo Badge, 56mm in diameter, silvered with white and translucent blue enameling. These were applied to aircraft engines and automobile grills, but that version had screw posts on the back. This version has prongs on the back for affixing it to an award sash, the cover of a photo album, or some other type of promotional item. I can't find anything else like it on the Internet.
