Occupancy sensors have two tasks: 1) Keeping the lights ON while the room is occupied and 2) Saving energy by keeping the lights OFF while the room is unoccupied. Passive infrared (PIR) is an excellent and precise technology for initially turning the lights ON, but lacks sensitivity for minor motion at distances. Ultrasonic (U/S) technology provides maximum sensitivity with continuous reflective high frequency waves. This is optimal for keeping the lights ON. Leviton multi-technology sensors combine the benefits of both PIR and U/S technologies for unrivaled performance and reliability.