1. An improved perforating device for affixing to an impression cylinder of an offset or lithographic press for perforating paper passing through the press comprising an elongated thin metal strip having a base portion of rectangular cross-sectional configuration having flat upper and lower surfaces and paralleled edges, the lower flat surface being adaptable to be affixed to a press impression cylinder such as by adhesive, and having integral upstanding teeth along one edge thereof extending substantially perpendicular to said base portion, said teeth being spaced apart from each other, and said base portion having notches therein between said teeth whereby said base portion is of reduced width at said notches, said notches permitting each of said teeth to flex individually as paper is forced thereagainst.