According to Lieber, "The concept of DI is to put plate imagers directly on the press. By doing so, the plates need to be protected because the press is a hostile environment. The plates are put in a roll inside the cylinder of the press itself. The plates are then rolled out as needed. Thermal imaging exposes the plates on the press. All four or five plates can be changed at the same time; fresh plates can be advanced in 20 seconds." By decreasing the time needed to change plates, DI lends itself nicely to printers specializing in POD and short run. In fact, CAP Ventures indicates that printers who use the DI system average higher profit margins than what National Association for Printing Leadership (www.napl.org) calls its highest performers.