The Hauck Adjustable Air and Gas Port Valves are a dependable, accurate means of controlling the flow of air or gas to any variable pressure type of burner or system. Flow control may be either manual or automatic. These valves are easily adjustable and designed to hold the desired setting in either mode of operation. Each side of the valve is equipped with four drilled and tapped mounting pads. This facilitates the installation of multiple valve units or an automatic control system. These units are designed to be used as efficient control systems, not as shutoff valves.