The Leviton WSC15-IRW 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 as an option for applications without available ambient light. For improved detection, the sensors use an enhanced PIR element located directly behind a unique multi-zone optical lens. This occupancy sensor as a total coverage of 1500 square feet and is Title 24 Compliant. The wireless receivers and transmitters are not included.