Abstract: An apparatus for protecting the printing cylinders of an offset printing unit against damage that can be caused by paper wrapping around on the blanket cylinder when there is a break in the web after it has left the printing unit. The apparatus includes a pair of web capturing inertial rollers between which the web passes, each of the rollers being freely rotatable and each have a plurality of circular web gripping rings which are in constant contact with the web so that the rollers are rotatably driven solely by the web. The gripping rings are laterally adjustable along the axis of rotation of their respective roller so as to permit the traveling web to be gripped in preselected positions in non-print areas.