The Outdoor Air Temperature Sensor is 10K based thermistor, which can be used as an accessory for select model thermostats and zoning systems. This sensor provides outdoor air temperature information for the control system, as well as an indication of outdoor temperature for the homeowner. The TSTATXXSEN01–B sensor is completely interchangeable with the older style Part No. TSTATXXSEN01. This sensor is improved for easier installation and wiring hook-up.