That was what I've been trying to figure out. It sounded kind of sketchy, like they were getting HP print heads, but not from authorized sources. I've talked to other people about that gray market.

If you don't have a single source or have multiple sources, you need to understand what happens when those inks mix in the delivery system. There are still inks in the tubes and in the print head. If you get two different inks in there, how do they react? Do they lessen the life of the print head or burn it out? There's a risk involved. If it says 20 liters, you have to test your ink. Companies like HP and Epson test for years and spend millions of dollars. It's up to the individual to decide how much testing to do. They might just say it's good enough and choose an ink to buy. These are unknowns when you don't have the back-end support of the technology owner like HP and Epson. So, those are the two ways people integrate systems