The Rheem-Ruud SP20875D Chamber Sensor Replacement Kit is a genuine replacement component designed to monitor combustion chamber conditions in compatible Rheem and Ruud gas water heaters. It works by detecting abnormal temperature levels within the combustion chamber and communicating with the control system to help prevent unsafe operating conditions. https://www.partshnc.com/sp20875d-rheem-ruud-chamber-sensor-replacement-kit