In WWI Germany at the time money was being horded thus creating a lack of currency in circulation so towns and cities minted their own local money to be used just in that city or town. There were probably thousands of different types of bills and hundreds of different types of tokens minted. It is Notgeld or 'emergency money'...some of the bills and tokens from this time have great designs, kind of like the earlier Conder Tokens in Britain. This one is no exception.

This coin was minted in Iron as other metals were probably in short supply and it was minted for the city of Duren...Stadt meaning city. This Token was probably only used in Duren and from what I have read even these were probably hoarded as well...