Uses Miniature Sonic Technology for discreet coverage. The unit emits high frequency sound waves that effectively repel rodents from protected areas. Nightlight offers extra security feature, and extra plug keeps outlet free. Perfect for homes, offices, summer homes, boats, restaurants, hospitals, farm buildings, kennels, stables, etc. The sound is completely inaudible to people and non-rodent pets. Varying intensity and frequencies of ultrasonic sound waves prevent rodents from getting used to the Victor Sonic PestChaser. Since the sound is inaudible, a red LED light tells you the unit is working properly. It's kinder than traps, safer than poisons, and there are no dead rodents to dispose of so it minimizes human contact with mice, rats, and other disease-bearing rodents. Reduction in rodent activity should occur within 6-10 days. Estimated service life of the unit is 5-7 years or more. Note: Ultrasonic sound cannot penetrate furniture, cabinets or walls. Multiple units required for multiple rooms.