Herbin, “The Jewel of Inks”, uses all natural dyes in their fountain pen inks. This natural composition is reflected in the very neutral pH of the inks in theseuniversal snap-in cartridges that come neatly and securely packed in a cylindrical metal tin. These fit most fountain pens and rollerballs, except Waterman, Sheaffer, Parker, Lamy, A.T. Cross, Pilot/Namiki, Sailor, Platinum, Aurora, Fultz and Nakaya.