Sophia Global Remanufactured Ink Cartridge Replacement for HP 21 (1 Black) Backed by a 100% Guarantee and a Two-Year Warranty ISO 9001 Quality Certified Manufacturing Process Page Yield: Up to 190 pages This HP 21 cartridge was professionally remanufactured in an ISO 9001 factory. This cartridge was used once and then sent to our factory where it underwent an extensive process including cleaning, testing the chip, and ink refilling. Before being sealed, the cartridge was tested in a live printer to ensure crisp text and true color reproduction. The cartridge was finally sealed and placed in a static protective bag.