1.Black thermistor probe is made of stainless steel, high temperature resistance, the wire contains high quality copper core with excellent conductivity 2.REPLACEMENT PART NUMBERS: 3-20-11744 3-20-00744 1-00-00744 3.WIDE COMPATIBILITY: 3-20-11744 Black thermistor probe fit for Harman Pellet Heatilator Furnace many models, including Accentra Cast FS, Accentra Insert, Advance, Invincible Insert, Invincible RS, P38 (P38+, PP38+), P61, P61A, PC45, PF100, XXV, BA100, etc 4. 3-20-11744 pellet stove probe measures accurate temperature, sensitive response, providing accurate measurement of temperature fluctuations and helping equipment efficient operation 5.INASTALLATION: Installed in the vent casing close to where the vent pipe connects Package Included： 1×.