I've been literally using the 901 black inks for years in my older OfficeJet 4500. I get great life out of them. BUT...I get "not nearly as good" life out of the 901 color cartridges.
I have had my hp Officejet printer for at least 6 years and it is difficult to find 901 ink cartridges. Ordering was easy and the price was cheap. thank you.
My printer only works with original black ink from HP. Tried refills and no joy. I don't print everyday but it's nice to not worry about whether it will print. The price was great (I hope it doesn't change-hint) and for original ink it wasn't much more than a refill. Thank you.