Occupancy sensors have two tasks: Keeping the lights ON while the room is occupied and saving energy by keeping the lights OFF while the room is unoccupied. sensors combine the benefits of both PIR and U/S technologies for unrivaled performance and reliability. Additionally, the sensor is designed with an isolated relay contact; which enables the sensor to interface with other systems (example: BAS, HVAC or any dry-contact capable device or system). Self-Adjusting: Internal microprocessor continually analyzes, evaluates and adjusts the sensitivity and time delay. Performance is kept at a maximum and user complaints are eliminated.