Get crispy, sharp and clear prints with the HP 21 Twin Pack ink, which ensures a standard quality from start to end. This HP black printer ink is capable of printing approximately 380 pages, before running out. Compatible with almost all HP printers, this HP ink cartridge provides consistent and high quality results. Get updates and alerts from HP SureSupply, when the HP 21 Twin Pack ink is running out of ink and needs to be replaced. This HP black printer ink produces superior and quick results, using less ink. This HP ink cartridge produces fade resistant and professional looking prints that offer long lasting results.