Serienscheine, or serial paper money, are a sub-set of notgeld. It had been found that, when the original notgeld were issued after the outbreak of the first world war, some people were collecting them due to their artistry and colourfulness. Local issuing bodies began to realise the opportunity, and started to issue notes after the pressing need for emergency paper money had passed. Many of them commissioned famous artists of the day to design the notes.
These were generally sold in sets, either in various denominations (mostly 25, 50 & 75 pfennig) or a variation of designs for single denomination (often 50 pfennig). Some issuers brought out many different sets.
These notes weren't issued for circulation and were often issued with a validity date that had expired before they were issued, generally between 1920 and 1922, before the hyper-inflationary period began.