A unique item, according to our findings currently the third known piece on the collector's market with a green NIEOBIEGOWE print.
Sold together with a card from a calendar for 1997, issued by a Dutch company.
The card for the month of July contains the banknote in question inserted in the holder, along with its description.
It is possible that the "Polish cities" were reprinted at the request of this company and given a green overprint at the time. Another theory is that there were trials of printing in different colors - for a test to see which would come out best (red printing was chosen at the time).
