Sonic PestChaser repellents emit high frequency sound waves to create an acoustically hostile environment that effectively repels rodents from protected areas. Blue LED (light emitting diode) indicates the unit is active. Contains a piezo system that features a ceramic membrane (versus paper), creating a louder sound and allows for better control of frequency. Sound is inaudible to people and non-rodent pets. Covers up to 400 square feet. Small discreet design is ideal for use in average-sized rooms, kitchens, garages, and basements. Ultrasonic sound cannot penetrate furniture, cabinets, or walls. Emits ultrasound at varying volumes and frequencies to prevent rodents from becoming accustomed to the sound. Multiple units required for multiple rooms. Provides years of useful operation. Ideal for environments where the use of poisons is inadvisable or prohibited. Ideal for homes, offices, summer homes, boats, restaurants, hospitals, farm buildings, kennels, stables, and more. Uses less than $.01 worth of electricity per day. Plugs directly into an outlet. Does not interfere with the radio, television, or other electronic equipment. Features a built-in night light.