Drive mice, rats, roaches, ants & other pests out of your home! Each chemical-free unit plugs into any standard outlet and uses ultrasonic waves to repel unwelcome critters without traps, poisons or harmful chemicals. Safe around people, cats and dogs; won’t interfere with TVs, remote controls or garage door openers. Each features an extra outlet with safety cover. Protects a standard size room. Set of 3. UL-listed.