Interesting badge here, worn by members of the Solidarity Arbeiter-Radfahrer-Bund (Workers-Cyclist Federation.) During the Weimar Republic, the Solidarity ARB had several hundred thousand members and was the largest cycling association in the world. The S (Solidarity) signified that the ARB was a socialist organization and part of the labor movement. A working pin and catch are on the reverse with the inscription, "Property of the Worker Cycling Federation - Solidarity"