Sonic Mini PestChaser electronic pest control device emits 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. Sound waves do not travel through walls, furniture, curtains, or other objects. Emits ultrasound at varying volumes and frequencies to prevent rodents from becoming accustomed to the sound. Miniature technology offers discreet ultrasonic pest control coverage. Package includes 2 miniature units for multiple room coverage. Plugs directly into an outlet. Do not use around rodent pets. Rodent pets include mice, rats, hamsters, guinea pigs, ferrets, and squirrels. Never install a PestChaser in rooms inhabited by rodent pets as the sound will cause your pet severe auditory stress.