I am an Osmiroid fan and there are mainly 3 types of Osmiroid calligraphy pens (plus dip pens).
1. One pen type has two gold colored bands on the cap or one bold painted line on cap. This type uses "easy-change nibs" & you can purchase "extra capacity squeezefills" (for bottle ink). Usually you can find on EBay. My daughter is using such a set presently, but she simply pushes "universal ink cartridges" on & they seem to do fine. I am very new at all fountain pen collecting & there are professionals on this site that could answer you questions better. But I hope this helps a little !
The two other pens are: 2. Osmiroid 65 (a lever filler) & 3. Osmiroid 75 (a piston filler) which use bottle ink. If you google the three types you might get a better idea of the type of pen and the many nib sizes & cartridges.
P.S. the "easy change" nibs look very different from the nibs for the 65 & 75 pens. n
Good Luck Osmiroid pens are great pens to work with!
Edited by Pen Pixie, 23 May 2008 - 16:52.