Electronic Ultrasonic Pest Repeller Pest Controller for Pest Reject Indoor Plug in Pest Defender of Spider Mice Mosquito Rats Roaches Rodent Insect(6 Packs) Efficient Ultrasonic TechnologyThis Ultrasonic pest repeller emits high-frequency ultrasound, causing pests to lose direction and consciousness and drive them away from your home. Human and Pet SafeIt is designed for environmental protection and 100% safe for human. No radiation, no chemicals, non-toxic, no smell and no noise. Just drive pests away without killing them, an environment-friendly and humane solution to keep the pests away from your home. Easy InstallationSimply plug the device in to household power socket vertically.Installing the devices 30-70 inch from the floor is recommended. The blue LED light illuminate,indicating the device is working. Widely Effective CoverageThis Ultrasonic Pest Repellent has a great effect in 160 square meters in the room. For 100 to 150 square meters of the area is effective. To make it work at the optimum level, we suggest installing one device in each room cause the sonic sound wave cannot get through walls. After Sale ServiceAs a reliable seller on Amazon, we always try our best to provide good quality products as well as excellent service for our customers. You may contact customer service team through our store page and click "Ask a question". We will always glad to help you if there is any query about our products.