Abstract: The present invention relates to a method, and means or device comprising an attachment, that is capable of quickly, efficiently, and accurately, horizontally aligning printing plates, especially offset printing plates on a rotary press such as an offset press, before the production run of the press. Set-up time is reduced to a minimum. The attachment may be removably affixed at a convenient location on the press in such a manner as to adjustably cooperate with the printing plate for horizontal alignment thereof, whereafter, the plate is locked in place, or hangs freely on the printing cylinder, and the printing job or run is started. Once the attachment or device guide is properly positioned, other or subsequent printing plates can be substituted for or changed with the first plate and quickly aligned, as the workload and variety of jobs for the day demands.