Cleaning tool kit for HP 51645A and HP C6615dn inkjet printer cartridges. Our print head cleaning tools pull air through the print head nozzles to open them up. It then pulls a small amount of ink through the nozzles to "flush" them and insure that the cartridge ink is pulled down close to the print head. You can use it to clean and to repair a cartridge which has stopped working or use it to restore a refilled cartridge. These tools come standard in most of our "Inktec" refill kits or you can buy them separately here.