The Standard ceiling sensors offer a wide range of basic ultrasonic occupancy sensors. They can be used to control lighting or small fans in rooms and corridors of various shapes and sizes. These models activate a switchpack to turn the loads on and off. Ultrasonic sensors are ideal in spaces where you need increased sensitivity to minor motion (like a hand waving) in larger spaces (>500 sq. ft.). Ceiling sensors are typically used in large or small spaces where wall switch sensor can not be used due to switch location, room orientation or furniture placement.