Pest Reject uses two advanced technologies: Electromagnetism sends electromagnetic pulses through the wiring in the walls of your home to create a hostile environment that makes pests pack up and go. The ultrasound waves emitted intermittently by the device make life unbearable for pests so they flee the area of action of the ultrasound waves. PestReject does not kills pests, but makes their life unbearable so they go away. Double Technology: Electromagnetism against Spiders. Ants. Cockroaches, Rats and Other Rodents. Ultrasound against Mosquitoes and Flies. Safe: Pest Reject is completely inoffensive for children and pests, and does not interfere with household appliances. Environmentally friendly: Pest-Reject is a product for home use that works 24 hours a day, 365 days a year with no hazardous chemicals that are toxic or poisonous or that give of noxious odors.