content: A few weeks ago, I bought a few disposable fountain pens to see if I liked them, and after a few days, I began using them as my primary pens. The problem was that they had (very) bad ink in them, so when I ran out of ink, I decided to attempt to refill them with Noodler's ink-- and it worked! This stuff is pitch black, and best of all, it doesn't bleed or "feather" when you're writing with it.Works well in:Pilot Varsity Disposable Fountain Pen Assorted Ink 7-Pack Pouch (90029)