Furnace Flame Sensor 62-23543-01 2PACK, replacement model: #62-23543-01,62-23543-02,62-23543-03,62-23543-04. This flame sensor is for Rheem & Ruud gas furnace, work with Rheem classic 90 plus, Rheem criteron II gas furnace etc. Working Principle: Detect when the burner flame ignites and send a signal to the control panel to stop the ignition. Length (mounting flange to sensor tip) 2-1/2", length-sensor offset: 1-9/16", Angle sensor offset: 90 degrees, Termination 1/4" male thread quick connect. Easy to install and made of high quality and hard wearing metals and ceramics, well tested and durable. Warming reminder: disconnect electrical power and shut off the gas supply before installing rheem furnace parts. Package includes: 2 pcs furnace flame sensors #62-23543-01.