Using the Greenfield Converter as a reuseable ink cartridge enables Greenfield Fountain Pens to be filled with ink from a jar instead of having the disposable plastic cartridge. The reuseable cartridge has a screwable syringe like effect that is easy to use by inserting the open end into the ink and turning the screw to suck the ink into the cartridge it is then wholly inserted into the pen as a cartridge of ink. It is a one piece structure so nothing can get lost.