These printers use the C9451A cartridge:

HP DesignJet Z-2100

HP DesignJet Z-2100-24 IN

HP DesignJet Z-2100-24 Inch

HP DesignJet Z-2100-44 IN

HP DesignJet Z-2100-44 Inch

HP DesignJet Z-3100

HP DesignJet Z-3100-24 IN

HP DesignJet Z-3100-24 Inch

HP DesignJet Z-3100-44 IN

HP DesignJet Z-3100-44 Inch

HP DesignJet Z-3100 PS 24 IN

HP DesignJet Z-3100 PS 24 Inch

HP DesignJet Z-3100 PS 44 IN

HP DesignJet Z-3100 PS 44 Inch

HP DesignJet Z-3200-24 IN

HP DesignJet Z-3200-24-Inch Wideformat

HP DesignJet Z-3200-44 IN

HP DesignJet Z-3200-44-Inch Wideformat

HP DesignJet Z-3200 PS 24 IN

HP DesignJet Z-3200 PS 24-Inch Wideformat

HP DesignJet Z-3200 PS 44 IN

HP DesignJet Z-3200 PS 44-Inch Wideformat

HP DesignJet Z-5200

HP DesignJet Z-5200 PS

HP DesignJet Z-5400 POSTSCRIPT EPrinter

HP DesignJet HD PRO