Victor M751 Mini PestChaser Ultrasonic Rodent Repellent For use in average size rooms, kitchens, garages, attics and basements Emits high frequency sound waves that effectively repel rodents Sound is completely inaudible to people and non-rodent pets Varying ultrasonic sound waves prevents rodents from getting used to the Victor Sonic PestChaser Since the sound is inaudible, a red LED light shows unit is working properly