Elysee fountain pens use standard cartridges; therefore all commercially available standard cartridges and corresponding standard converters fit without problem. Only Lamy, Parker, Sheaffer, Dupont and Cross have their own proprietary sizes. Montblanc cartridges have a slightly different shape but also fit into all fountain pens with standard cartridge intake. Today's Montblanc converters, on the other hand, have had a thread for a good ten years, which is why their suitability for other brands is restricted.