Hi Alex:
This is a customs officer helmet not police. We can tell this from the tulip shaped spike and the wappen (helmet plate) which bears the royal cypher on the bird. Thie piece is also missing its kokarden. At the very least, there should be a Reichs kokarde on the helmet where the chin scales attatch. Other than that, it looks fine to me. I believe that I posted a picture scan of a customs officer wearing this type of helmet on the "period photos" part of the forum. Regards, Brian