Sonic PestChaser electronic pest control device emits high frequecy sound waves to create an acoustically hostile environment that effectively repels rodents from protected areas. Sound is inaudible to people and nonrodent pets. 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.