Kaweco Mini Piston Converter for Fountain Pens
This clever gadget allows you to use bottled ink in your Kaweco Sport. It is not recommended for the Lilliput.
It's an improvement on the squeeze - but be warned. It's a bit fiddly, and you do not get a lot of ink per fill.
I love my bottled ink and I remarked to Kaweco that I was surprised that a German company hadn't been able to engineer a better solution. The response was swift.
"We did. We called it a cartridge."
That's me told.
In geek mode, I syringe-fill the converter. Road Warrior mode, I use a cartridge.