Hard to Find Waterman CF ink cartridges. These are the cartridges required for the CF fountain pens (among others):
Since the converters for these models are virtually impossible to find, these dried-up (but unpunctured) refills can save the day as they can be refilled with ink via a syringe (not included).
This listing is for a pair of un-opened cartridges, in black or blue. Some look like the ones in the photos with red tips and metal ends, and some are all clear plastic.