These cartridges are special carts that epson techs have.
Basically they are cartridges without ink-bags or internal dampers. They depress (open) the inlet spikes in the printer bay to allow air into the lines. Then the printer does an "initial fill" but instead of with ink it's just air. This ejects the ink from the system. This is a dangerous procedure that should only be done after a full purge with PiezoFlush or actual Epson Cleaning Solution that is really only available in the factor. It's done when "re-furbishing" an Epson printer for re-package and re-sale on the refurb site.
In the past (in my own labs that I've run) I would take a color printer, fill with PiezoFlush, let that sit for 24 hrs, then put Epson carts in that I had modified to not have ink bags, then I would do this ink eject procedure to get rid of the red PiezoFlush, and then I would init-fill with Piezography ink. In my mind, this would eliminate any small excess red that was present from the PiezoFlush after the Piezography ink was in the system.