This Honeywell Duct Mounted Temperature Sensor is a precision instrument designed to measure temperature within HVAC ductwork. The sensor features a 12-inch probe length, which allows for accurate readings in various duct sizes. It utilizes a 20K ohm NTC (Negative Temperature Coefficient) thermistor, known for its high sensitivity and accuracy in temperature detection. The device comes with an enclosure, providing protection against environmental factors that could potentially affect the sensor's performance.