membership badge ?? help wanted

[marc b]

Hi,
Is there someone who can tell me more about this one?
I can't find back what it's for.

Thanks!!!
Marc

[Gerdan]

R.D.K = Reichsbund der Kinderreichen - State Federation for large families

Gerdan

[James Noble]

Marc.
You have a very nice original example.
The RDK Reichsbund der Kinderreichen (State Federation for Large Families) was in place until at least 1937 when it was replaced by the RDF (State Federation for German Families).