Leviton's ossmt multi-technology decor a wall switch occupancy sensor is used to provide automatic lighting control for energy savings and convenience in a variety of commercial applications. Occupancy sensors have two tasks: keeping the lights on while the space is occupied and turning the lights off when unoccupied. The pir sensors provide immunity to false on through a specialized Fresnel lens which divides the field-of-view into sensor zones. When a person passes into or out of a sensor zone, the sensor detects motion and automatically switches the lights on. Once the specified time-delay has expired, the sensor will automatically shut the lights off. The ultrasonic (U/s) sensors provide maximum sensitivity and range in difficult spaces with irregular shaped rooms and partitions that can block the pir field-of-view. A pair of U/s sensors will detect Doppler shifts caused by motion in a space preventing false off. These sensors are more sensitive to small movements since they do not rely on zones.