Here is a rundown on the various converter that fountain pens take.  The converters are essentially a mechanism to pull ink from the ink reservoir.  It can be inbuilt ( inbuilt to pen  - like piston mechanism etc) or can be something which can be detached.  

So Fountain pen converters which can be detached are divided in the  following based on its functions:

• ​Piston converters use a twisting motion to push air out and then pull the air/ink back with twisting it counter clockwise. These are more popular.

• ​Squeeze converters usually use a squeeze mechanism on the bladder to pull ink from ink bottle .

Different manufacturers had different converters.  But over the years, a bit of adaption is in progress and International converters can be used on many pens.  But some pen companies still use their proprietary ink converters.  That below chart helps you to get an additional converter or a converter based upon the pen model.  The list is not comprehensive but will cover most of the brands we carry.   

​Standard International converter - Typically around 3 inches long, they are at this specific standard.  Important to note is the push type and screw type.  Most of the generic pen brands use this.  

Fountain Pen Converter Guide

Note: While a majority of fountain pens can refill with standard international converters, some models may not. This fountain pen converter guide is meant as a recommendation. Please refer to your specific pen’s instructions for acceptable converter sizes.