The success of their expanded Itf and Gemstone ink collection, Monteverdi USA announce their new 12 piece ink cartridge sets, which is now available in 31 brilliant Fountain Pen ink colors. Each set of cartridges are standard international size and are individually packaged in a thin, hangable and reusable plastic container. Perfect for any fountain pen lovers, you need your favorite MONTEVERDE ink always within reach. Each cartridge is made with MONTEVERDE usa's European ink treatment formula (itf).