Standard Black ink. Compares to HP C51645A. For use in non-demanding applications. Best used on porous materials. This comes with a 370ml Bulk Bladder, 42ml Print Head Cartridge and Connector Hose. The cartridge is a remanufactured product of the USA. Used in most envelope/address printers from Pitney Bowes, Neopost, Rena, Secap, Astro, Asmarc, FP Mailing Solutions, Buskro, Kirk-Rudy and MCS.