Fireboy®-Xintex® has designed a line of liquid level gauges that are built to the quality standards of all our equipment. Senders are available for either threaded or flanged top-of-tank installation. Choose either one-tank or two-tank monitors with appropriate threaded or flanged senders. Order online or call our factory at 1-866-350-9500 for Assistance and Technical Information. Not interchangeable with the WTG System Series, which are three-wire connections. (These items have two-wire hook-ups.)