Front and rear printers for use with a document transport mechanism. The printers are identical in construction with each having a compact housing in which the associated print head is mounted. The housing has first and second side walls, a front wall which also functions as a guide for guiding documents to be printed upon therepast, and a rear wall which functions as a circuit board which houses the driver electronics assocated with the printer. The print head (ink jet) is mounted on a carriage which is moved within the housing in a first direction which is perpendicular to the direction in which the documents are moved in a document track past the printers. The front and rear printers are detachably mounted on opposed sides of the document track to enable the printing of alphanumerics or graphics on the front or the rear of a document moving thereby.