How long do these cartridges last? That is the most important question today. You need to check the number of pages on these remanufactured cartridges. I've bought 4 XL black ink cartridges (61) and one original HP 61 cartridge since January and I'm not sure I've printed enough black and white pages to fully use the black ink. My durability question aside, Greenbox remanufactured products offer excellent print quality and a very good price.