The Leviton WSC04-I0W wireless occupancy sensor responds to any source of heat within the range of detection, including heat emitted by a human body. It is battery free and can operate in total darkness for up to 48 hours. Batteries can be added to have continuous uninterrupted AUTO-ON operation. This occupancy sensor has a total coverage of 450 square feet and is Title 24 Compliant. The wireless receivers and transmitters are not included.