content: I have an HP Officejet 6210 and I figured I'd try this refill for my 94 ink cartridge. Filling it up was a pain because I had to hold the refill needly just barely into the created hole and let it drip in there slowly. My biggest problem was that after I refilled my cartridge, my printer would not let me use it anymore. I kept getting an error message that said "Please remove and check your black ink cartridge". I tried cleaning it, resetting the printer..tried everything to no avail. I contacted the manufacturer of the refill system and they rapidly sent me a new one, which I haven't tried. Now I need to buy a new ink cartridge for my printer to even operate! Very disappointed.