*Original HP 936 ink cartridges page yield tested in HP OfficeJet Pro 9120 series vs HP 962 ink cartridges tested in HP OfficeJet Pro 9020 series. Average continuous printing yield of black and composite color (cyan/magenta/yellow) based on ISO/IEC 24711 or HP testing methodology. Actual yield varies considerably based on content of printed pages and other factors.This printer is intended to work only with cartridges with original HP chips or circuitry and will block cartridges using non-HP chips or circuitry. Periodic firmware updates will maintain the effectiveness of these measures. More at hp.com/learn/ds.