Pneumatic Tube Mail Munich Germany
According to a reference list - published 1927 - from the German company Mix & Genest AG, Abteilung Rohrpost und Förderanlagen in Berlin-Schöneberg, the German city of Munich had access to a Pneumatic Tube Mail system with 48 stations and a tube length of 46 kilometers.
Later on the system was expanded with another 16 stations and 8 kilometers tube.
Postamt München 9
Stamped 20 April 1957