The PHC case is the main structural part of the replacement module. It is the part that the customer handles and contains the other sub-components:

-Wiper to remove ink residue and external debris from the Printhead.
-Spittoon to receive ink from the firing Printheads when the nozzles are cleared of viscous plugs and any loose debris.
-Cap to prevent the Printhead nozzles from drying out while the Printer is idle.
-Handle and Printable Label to remove and install the PHC. Also, the printer uses the handle top surface to recognize if the PHC is present or not.

In addition, there is a built-in mark on the handle (a vertical hole) to calibrate the Service Station (Scan-axis) if there is a problem and the EEROM is erased.