This sensor can be used to replace the one that came with your Ranco ETC digital temperature controller or multiple sensors can be wired for average temperature sensing. See the instructions for your controller for wiring instructions and recommendations. This sensor is designed for use with ONLY Ranco ETC temperature regulating controls. It is a negative temperature coefficient (NTC) thermistor sensor. The sensor resistance decreases with temperature increase. It is 0.25" x 1.94" long with 8 feed of #22 AWG cable. The thermistor has a reference resistance of 30,000 ohms at 77°F(25°C). Supports temp range of -30°F - 220°F Note: The manufacturer does not recommend the sensor be directly submersed in liquids. They recommend using a thermal well (bulb well) to protect the sensor.