If you are shopping for ink cartridges and do not have a used cartridge for reference, look for your brand of pen in the list of cartridges. If you cannot locate your brand, many fountain pens have been designed to fit the international-sized ink cartridges. They are one and one-half inches long and fit in most barrels. They also have a uniform "neck" which fits in many fountain pens. We carry numerous brands, all of which contain the water-based liquid ink commonly used in fountain pens. Colors abound in either the Colorado Pen or Pelikan brand.
If you are shopping for bottled ink, Colorado Pen carries premium Edelstein ink from Pelikan, our own exceptionally large bottles of Colorado Pen, Waterman or Pelikan standard ink. All of these are available in a wide range of colors.