HP 72 130ml Gray Ink Cartridge (C9374A)
HP had transit the old SKU of this ink to new SKU, as below:
HP 72B 130ml Gray Ink Cartridge (3WX08A)
Suitable for HP Designjet:
T770 / T790 / T1200 / T1300 / T2300 Series Printer
Users must upgrade their printer’s firmware to be able to use the new part numbers, otherwise the printer will not recognize them. Printers updated will continue to accept current supplies as well as the new ones (with and without B). Firmware can be found in this URL and only needs to be done once per printer: www.hp.com/go/designjet/firmwareupdate
For any enquires, please call HP Support Care Line: 1800-88-8588 for further assistance.
HP DesignJet T620, T1100 and T1120, currently using HP 72 supplies family, cannot have a firmware upgrade that allows the use of the new cartridges. Therefore, they will no longer have compatibility with HP inks from this onward. The end of support for these printers was on April 2016.