For use in average sized 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. Reduction in rodent activity should occur within 6-10 days. Multiple units required for multiple rooms.