Most fountain pens that require a half-length ink cartridge and which use the international standard size will easily accept the Templar Ink Mini converter. However, we do know that it will not fit the Kaweco Sport, the Visconti Van Gogh Mini Pen, the Montblanc Mozart 114, or the Monteverde Tool pen. These pens require a thinner converter body and will require the Templar Ink Skinny-Mini converter. There may be other pens that use a thinner converter body. If you have any doubt, please refer to the below chart and measure your pen before purchasing a converter.