Regardless of the technology used, one of the key factors in the design of a printing device is the interaction between the printing medium and the rest of the printing system. This is especially true in the case of inkjet printing technology, where the interaction between the printing medium and ink is critical to achieve good level of printing and color quality. This means that a large number of printing parameters depend on the printing medium being used and have to be adjusted for each specific substrate. This paper describes the Open Media System, implemented in the HP DesignJet 5500 large format printers, which forms part of the HP DesignJet product family, that allows the support of a wide and dynamic set of media types. It is based on a highly flexible set of software components (print mode engine, contone to halftone imaging pipeline, media selection user interface…) that are configured using a database of media profiles that hold all the parameter settings required to configure those components to print on a specific printing medium. Media profiles can be created, downloaded to printing devices and managed using software tools specifically developed for these purposes.