The CheckBox is a secure printing device designed to store print resources such as forms, fonts, secure digital signatures, and logos in non-volatile flash memory on a removable secure card. Because the secure card and the resources it contains can be kept in an appropriate secure location, users have absolute security against unwanted printing of documents such as checks, drafts or other such documents. The module is packaged in a small enclosure that has a parallel input, a parallel output port and convenient provisions for the card.

In normal operation the module's output is connected to the standard parallel port of any HP PCL or compatible printer and its input is connected to the printers data source. When the resources are needed for secure check printing, the card is plugged into the module. After verification the resources in the card are automatically loaded into the printer.

When secure check printing is complete and the card is removed, all resources previously loaded into the printer are automatically deleted. Printing is unaffected by the module because it is transparent to all host data streams.