Time expired

I was looking through some papers today that once belonged to my great grandfather.  He visited Cologne (Köln) in 1922 and must have brought back these paper tokens.  I had initially thought that they were 50 pfennig (100 pfennig = 1 Mark) pre-devaluation currency notes but it seems that they are local tourist tokens.  On the other side is writing in old german script that translates to, "This credit note can be used as payment against all municipal tickets.  It loses its validity on 15 August 1922.  The Principality of Köln is liable for the cash.  Köln12 January 1922, Chief Executive."