If you are planning to use a Venstar Wireless Indoor/Outdoor Remote Temperature Sensor for temperature reading, the Venstar Wireless Sensor Receiver is a required interface. The sensor receiver will work with a Venstar 1-Day Programmable Digital Thermostat, 7-day Programmable Digital Thermostat and 7-Day Programmable Thermostat, Dual Fuel, each sold separately. It hardwires to one of previously motioned thermostats, and once wired, is designed to hang inside the wall where the thermostat is mounted. The unit receives wireless transmission from a temperature sensor via radio frequency (RF), automatically averages the temperatures it receives, and reports the average to the thermostat for display. The sensor receiver has four LEDs that act as a diagnostic tool to confirm reception and makes programming a breeze. It can receive and average up to eight different temperature sensor units programmed to the same house code.