Pelikan C499 Converter for Fountain Pens, Universal Refilling Ink from The Bottle, All Standard Pens Various Manufacturers

Amazon

Suitable for all Pelikan and many other fountain pens. Pack of 1, capacity: 0.75 ml. Allows you to use ink from ink jars with fountain pen cartridges. Piston converter with twist mechanism.

Brepen

The Pelikan converter is suitable for almost all Pelikan fountain pens and, thanks to its standard size, it also fits most other fountain pens.