Harman & Heatilator Exhaust Thermistor ESP Probe Fits Models: Harman Pellet Stoves: ~ Accentra Cast FS (Pre Serial # 00840167) ~ Accentra Insert (Pre Serial # 008241201) ~ Advance (Pre Serial # 008360001) ~ Invincible Insert ~ Invincible RS ~ P38 Pellet Pro Plus (P38 +) ~ P61 (All Models, including those that have a red and white wire ESP) ~ P61A (Pre Serial # 008085803) ~ P68 (Pre Serial # 008280309) ~ PC45 (Pre Serial # 008055031) ~ PF100 (Black Wires) ~ XXV (Pre Serial # 008206292) Harman Coal Stoves: ~ DVC 500 (Pre Serial # 008065076) ~ 44 Magnum Heatilator Eco-Choice Pellet Stoves: ~ BA100 (Black Wires) Part Numbers: ~ 3-20-11744 / 3-20-00744 / 1-00-00744 Specs: ~ Exhaust thermister probe, ESP, Black Wire. There are 2 different thermister ESP probes for the Harman line; one has a black wire, one has a red wire. You must order the same color thermister probe as the one you are replacing. ~ 120V AC ~ Mounts in the exhaust housing near the vent pipe connection. Clean at least once per season. ~ Exclusive 90 day manufacturer warranty with our no hassle replacement guarantee ~ Made in the USA