Water Source 1-1/4 In. MPT Air Volume Control for Deep-Well Submersible Pump. It is used with submersible pumps to maintain the proper relationship between the volume of air and water in a galvanized pressure tank. It is not used with precharged tanks. It has a durable plastic body, a polypropylene float, a 1/4 In. pressure gauge port, and a 1-1/4 In. MPT connection. The air release valve is non-adjustable.