25 Pfennig

This note is part of the vast German Notgeld phenomenon — the emergency small-change coinage shortage that gripped Germany after World War I drove thousands of municipalities and districts to issue their own paper denominations, often in the 10 to 50 Pfennig range. The joint issuance across three administrative districts simultaneously — Bonn-Stadt, Bonn-Land, and Siegkreis — was a practical workaround, spreading production costs through M. Dumont Schauberg, the Cologne publisher better known for printing the Kölnische Zeitung.

The "b" variant suffix in the DeNG reference indicates a distinguishing detail within the type — likely a serial number range or paper batch distinction catalogued by specialist researchers after the fact.