Each pack of Pelikan 4001 Royal Blue TP/6 cartridges contains six Standard International Short cartridges. Each cartridge contains about 0.75 ml of blue colored fountain pen ink.
Standard International Short cartridges are 38 mm long and would fit a lot of different cartridge/converter fountain pens. Most notable: Pelikan, Kaweco, Faber-Castell and Graf von Faber-Castell, Visconti, Caran d’Ache, Delta, Diplomat, Montblanc, Montegrappa, and many more.
If you are using a piston filler pen or a fountain pen converter, check out our great selection of bottled inks.