Cartridges
From WikiPenia for PenBoutique
Most European fountain pen brands (for example Caran d'Ache, Faber-Castell, Dupont, Montegrappa, Stipula, Yard-O-Led, Pelikan, Waterman, Montblanc, Monteverde, Delta and Rotring) and some pen brands of other continents (for example Bexley, Retro51, Tombow and Acura) use so called "international cartridges" (AKA "european cartridges" or "standard cartridges" or "universal cartridges"), in short or long sizes, or both. It is to some extent a standard, so international cartridges of any manufacturer can be used in most fountain pens that accepts international cartridges. Also, converters that are meant to replace international cartridges can be used in most fountain pens that accept international cartridges. Some very compact fountain pens (for example Waterman Ici et La and Monteverde Diva) accept only short international cartridges. Converters can not be used in them (except for so-called mini-converters by Monteverde).
Many fountain pen manufacturers have at various times developed their own proprietary cartridges, for example Parker, Lamy, Sheaffer, Cross, and Namiki. Fountain pens from Aurora, Hero, Duke and Uranus accept the same cartridges and converters that Parker uses and vice versa. Cartridges of Aurora are slightly different from cartridges Parker. Hero, Duke and Uranus have made few fountain pens that take international cartridges. Corresponding converters to be used instead of such proprietary cartridges are usually made by the same company that made the fountain pen itself. Some very compact fountain pens accept only proprietary cartridges made by the same company that made that pen, for example Sheaffer Agio Compact and Sheaffer Prelude Compact. It is not possible to use converter in them at all. In such pens the only practical way to use another brand of ink is to fill empty cartridges with bottled ink using a syringe.
