A rare late 19th early 20th C German ear trumpet. I have not seen another of these although judging by the markings there must have been others made.
It is a variation of the classic two piece telescopic trumpet which has been modified to have a flat base to allow it to stand without support. The ear piece also has a matching mirrored flattened section. Made from galvanised brass and marked ‘Planofex. Ges Gesch. DRGM’.