Abstract: An air supply and exhaust grill which requires no tools or fixtures for assembly of the components thereof and which provides for convenient manual adjustment of air flow therethrough. The device is preferably circular about a longitudinal axis to facilitate connection to a round air conduit and to provide a distinctive finished appearance, and includes an outer an an inner housing each having a main tubular portion and a radially extending flange. The inner tubular member is frictionally adjustable axially within the outer housing so as to control the air gap between the two flanges. Mating notches and stop are also provided between inner and outer housings which are selectively engagable by rotation of the inner housing.