The Brookstone® Ultrasonic Pest Repellers - Multi-Room, Plug-In, Set of 6 provides a safe and effective way to shield your home from unwanted visitors. This versatile set includes Micro, Classic, and Extra outlet design units to offer multi-room home protection for any space. These plug-in pest repellent devices use advanced frequency technology for chemical-free pest control that is odorless and safe for the whole family. Simply plug them in to enjoy a worry-free environment in your kitchen, hallways, or garage.