If you are using normal brown PET home brew bottles then you can't go past one of these in each bottle:
View attachment 41188
I do all my PETs that way and even all my competition entries if they are a bottle conditioned job. God designed them to fit exactly through the top of any PET bottle.
Pilsner, Pilsener or Pils comes from the Czech town Plzen so the OP was
almost there. The city was part of the Austro-Hungarian empire for a long time and it was known by its German name Pilsen before reverting to its indigenous name following the collapse of the Empire during the First World War. In fact they were the mob who sparked the War with the assassination of their Archduke Franz Ferdinand, often mistakenly confused with the Emperor Franz Josef - I expect Franz was their equivalent of Britney or Corey in those days - by a Balkan freedom fighter / terrorist. That's why my Grandad got shot up at the Somme "Show me your scars again Grandad" . Bastards.
Pilsner is the 'contracted' German form of 'from or pertaining to Pilsen' - Zwickel could maybe put us right here.
When the famous golden beer spread around the world it was called by variations on the Pils theme, being contracted even further in Germany where one just asks for "Ein Pils".