Sailor Ink Cartridges - Souboku Nano Blue-Black Carbon chronicle and it's easy to see

and it's easy to see why

Brass model should not be converted into the eye-dropper method as the ink can react with the metal

It has a liquid

giving it a significant weight

Blackwing Pearl (Pack of 12)

Sailor Ink Cartridges - Souboku Nano Blue-Black Carbon chronicle and it's easy to seeSailor Ink Cartridges Souboku Nano Blue Black Carbon Sailor proprietary fountain pen ink cartridges for on the go ease. These high quality nano ink are produced to create an ultra dark, deep line. 12 cartridges in a pack. Also available in Kiwaguro (Ultra Black), and Seiboku (Ultra Blue Black). For a more detailed review of this ink (in bottled form), please check out our blog.