The Wattstopper FS-155 is a line voltage PIR fixture-integrated occupancy sensor providing 12-foot diameter coverage for automatic on/off lighting control in commercial spaces including offices, restrooms, and storage areas. The built-in relay operates directly on line voltage, eliminating the need for a separate power pack and simplifying wiring for contractors. Its low-profile design integrates discretely into the fixture for applications where a clean architectural appearance is required.