The Honeywell KTTBA002 500kW Long Sensing Tube VMU is a stainless-steel sensing tube designed for use with Honeywell VMU500KW Venturi Mixing Units in commercial and industrial gas-fired heating equipment, including gas boilers and premix burners. It connects the venturi inlet to the gas valve regulator, transmitting pressure information that helps maintain accurate gas-to-air mixing d... https://www.partshnc.com/honeywell-kttba002-500kw-long-sensing-tube-vmu