Kaweco Mini Foldable Converter

Kaweco piston converter for Kaweco Sport fountain pens, Kaweco Liliput, and also the BENU Pixie, thanks to its foldability! 

This miniature piston converter allows the use of bottled inks with Kaweco's compact fountain pens that can normally only use short international standard cartridges.

So how does a folding converter work? All you do is fit the converter into your pen as normal, fill it with ink and then fold the piston over so it fits inside the barrel of your pen. It holds just as much ink as Kaweco's mini (non-folding) piston converter. 

Genius.