Thornton's ink cartridges have a neutral PH, excellent coverage, smooth flow for effortless writing. The international standard cartridges fit almost every cartridge converter fountain pen. The 12 ink cartridge for fountain pens features a plastic reclosable case that will help preserve the life of the unused cartridges. Each ink cartridge is 38.46mm long and 7.06mm in width, great alternative to an ink converter. This blue fountain pen ink cartridges lends expression to any writing or drawing ideal for calligraphy, taking notes in a journal or diary, and official business. Description : Lends expression to any writing or drawing ideal for calligraphy, taking notes in a journal or diary, and official business. This ink cartridge attaches to the back of the fountain pen feed and supplies the pen with ink. When the ink cartridge runs out of ink you simply remove the empty cartridge, throw it away and insert a fresh one. Convenient and Mess free fountain pen ink cartridges ink cartridges they are easy to carry and easy to use. Filling the pen does not require dipping the pen in an ink bottle. These ink cartridges work with the following pens: Acme, Ancora, Bexley, Bosserrt & Erhard, Caran d'Ache, Cartier, Colibri, Conklin, Conway Stewart, DaniTrio, Daniel Hetcher, David Oscarson, Delta, Diplomat, Dunhill, Elysee, Faber Castell, Inoxcrom, Itoya, Jean Pierre Lepine, Jorg Hysek, Kaweco, Krone, Latex, Libelle, Lominchay, Marlen, Michel Perchin, Montegrappa, Monteverde, Nemosine, Nettuno, Northpointe, OMAS, Osmiroid, Pelikan, Recife, Reform, Retro 51, Rotring, Schmidt, Schneider, Sensa, Sheaffer, Signum, S.T. Dupont, Stipula, Stypen, Taccia, Tombow, Underwood, Visconti, Waterford, Waterman and Yard-O-Led.