Abstract: An apparatus for use in a pipeline is disclosed. The apparatus has a housing through which pipeline fluids may enter from the rear of the housing, pass through the housing and subsequently exit from the housing. A first bonnet, having several openings, is mounted at the front of the housing on a shaft which is oriented parallel to the longitudinal axis of the housing. A second bonnet is mounted on the housing and fits over the first bonnet. The second bonnet has openings which, when aligned with the openings in the first bonnet, permit the flow of pipeline fluid out of the housing in various directions. The first bonnet is movable in relation to the second bonnet so as to vary the degree of alignment of the openings in the bonnets. By varying the degree of alignment of the openings in the bonnets, the flow of fluids through the housing is regulated so as to control the speed of the apparatus.