A hybrid paper-polymer banknote or Composite Substrate is a banknote made from a mixture of paper and polymer substance.
A polymer patch/band is applied vertically over the entire height of paper banknote, thus creating a clear window.
Bulgaria was the first country to produce a hybrid paper polymer banknote, in a denomination of 20 Bulgarian Leva in 2005.
[1]Manufactures of hybrid banknotes include Giesecke+Devrient's Hybrid[2] and Varifeye,[3] De La Rue's Optiks,[4] Louisenthal's Hybrid,[5] Landqart AG's DuraSafe[6] and Banque de France's EverFit.
[7] The countries and monetary unions which use hybrid banknotes include: