Abstract: The specification discloses a pipeline pig comprising an elongated cylindrical member having a front end and a rear end; a plurality of spaced annular flexible rings circumscribing the member and extending radially outward from the member for contacting the inside wall of the pipeline; and an elongated central aperture extending from the rear end of the member to a point beyond its midpoint and near the front end thereof for receiving fluid pressure to facilitate movement of the pig through a pipeline.