9 of 9 people found the following review helpful
HP Black Ink Cartridge No. 21,
This review is from: HP 21 Black Original Ink Cartridge (C9351AE) (Office Product)
I use my home computer and printer regularly in my work, and have always had excellent results with these cartridges. (The printer will not tolerate the cheap versions, so I have to get the real thing.) I'm printing mostly drafts, but I find that draft/economical quality printing is perfectly adequate for actual letters, etc. as well. I only change the setting to normal quality for documents I need to photocopy. At draft quality, the cartridges last for dozens of pages after the 'ink low' warning comes up, which is helpful when doing a long document.