Collet Pen Holder vs. Cheap Refills

The three collet pen holders I got a while ago came with ink cartridges:

Collet pen holder
Collet pen holder

So I bought three bucks worth of a dozen pens to get pretty colors, whereupon I discovered they didn’t fit into the collet. Turns out the locating flanges aren’t in the same place along the cartridges:

The flanges on the top cartridge have been shaved down perilously close to the ink, but it now fits into the collet.

Bonus: a dozen fairly stiff springs that are sure to come in handy for something!