20 Francs 9th series

Switzerland's 9th series was years late. Development began around 2005, but persistent technical problems with the Durasafe substrate — a polymer-paper hybrid that neither De La Rue nor any other major security printer had successfully deployed at scale — pushed the first release to 2016, roughly a decade behind schedule. The SNB had publicly committed to the series long before it could actually deliver it, an unusual admission of difficulty from an institution not known for stumbles.

Durasafe allows a genuine transparent window within a paper-feel note, something traditional cotton-fibre banknotes cannot achieve. The 20 Franken was among the first denominations released from the series.