Abstract: A portable print head module dedicated to one type of printing, for example rotary screen printing, for functionally replacing one print head, dedicated to another type of printing, for example flexographic printing, in a rotary printing press having a number of spaced apart print head stations for transferring multiple images along the length of a continuous web substrate. The rotary print head module is installed by partially retrofitting one of the print head stations. The module can be moved to functionally replace any of the print heads in the rotary printing press. A non-rotating impression bar can be used to back the continuous web instead of a rotatable impression cylinder. A cushion of air is formed on the backing face of the impression bar on which the continuous web can ride.