Norcold's 638391 Thermistor Assembly is compatible with all Polar N7, N8 and N10 refrigerator models. A Thermistor senses the refrigerator's temperature inside the fresh food compartment and tells the fridge whether or not to turn on or off to reach the desired temperature. This Thermistor Assembly has a 4-prong connector that snaps into the light fixture at the light bracket for easy installation. The other end of the thermistor should be clipped onto the tenth fin from the right side. It is recommended to replace the clip as well. Refer to manufacturer recommendations to ensure proper fit and usage. Quick and easy installation.