Abstract: An improved pig for use in a pipeline is provided in which the basic structure including a body and the cup portions integrally formed of a unitary design, the body being of an elongated cylindrical configuration, including at least a forward and rearward cup extending from the body, the diameter of the cups being at least two and not more than five times the diameter of the body, the normal diameter of the cups in non-used condition being slightly greater than the internal diameter of the pipeline for which the pig is dimensioned and the length of the body being at least 11/2times the normal diameter of the cups. In a preferred arrangement the body is hollow or tubular for a substantial portion of its length and has an insert of a tubular rigid material; the thickness of the cups is less adjacent the body and the increases in thickness towards the peripheral surface; and the rearward cup has pressure equalizing openings.