The FSP-211B is an IP66 rated motion sensor that dims lighting from high to low based on movement. Three configurations are available. The FSP-211B mounts inside the fixture and the PIR lens connects to the FSP-211B through a 1.30"diameter hole in the bottom of the fixture. The FSP-211B-S mounts to a fixture/enclosure with a 1/2" knock out, via a nipple on the back. TheFSP-211B-D has a drop mount nipple, for mounting on to a pole, or to a fixture. The sensor uses passive infrared (PIR) sensing technology that reacts to changes in infrared energy (moving body heat) within the coverage area. Once the sensor stops detecting movement and the time delay elapses, lights will go from high to low mode and eventually to an OFF position if it is desired. Sensors must directly see motion of a person or moving object to detect them, so careful consideration must be given to sensor luminaire placement and lens selection. Avoid placing the sensor where obstructions may block the sensor?s line of sight. The FSP-211B operates single phase at 120V/230V/240V/277V. No power pack is required. It is designed to be installed in indoor and outdoor environments.