With these HP Smart Tank ink bottles, you can easily refill the ink tank of your Smart Tank printer without spilling. The HP 31 and HP 32 ink bottles fit in multiple Smart Tank models. The nozzles that allow you to refill the ink, only fit on these printers. Make sure to properly check which printer series you have first, so you always buy the right ink bottle. Not sure which printer model you have? Check the manual or find it on the printer.