What is the correct converter to fit my Inoxcrom fountain pen? My grandfather left me an old Inoxcrom fountain pen that was given to him as a gift. I have been using it as a dip pen to write with, but am hoping to find a converter so I can use it on the go. I am not interested in cartridges.

I can't seem to find the model of this pen online, and it doesn't seem to fit the standard cartridge/converter size. The reason I say this is because I bought a fountain pen from an old man who hand makes them, and I suspect he sizes them to international cartridge/converter sizes.

Here are some photos of the pen:


Nib says Inoxcrom Iridum, ring around barrel says Inoxcrom, Spain written on gold part of lid.


There are no logos or symbols on ends of cap or pen.
Seems like everything online says these use the Standard International size cartridge. There are some complaints of leaks though unless you get them from the original maker. 

If you have an old original cartridge, you could try cleaning and refilling it.