How it works - this Ultrasonic Pest Repeller emits ultrasound at a frequency of 22 - 45khz via an ultrasonic and electromagnetic dual chip which interferes with the brain and auditory nervous system of pests and protects your home from pests, mice, rodents and mosquitoes. Easy to use - the repellent is simple to use. All you have to do is plug the ultrasonic insect repellent into a power outlet and it will start insect repellent when the blue night light comes on. It is recommended to install this insect repellent between 30 - 50 inches from the ground ( for flying pests) and 10 - 30 inches off the ground (for crawling pests). Wide effective coverage - mosquito repellents can have a working area of up to 1200 square feet; Since ultrasonic cannot penetrate walls and solid objects, place mouse repellent in every room, 6-12 units is enough to repel pest control indoors (depending on severity of infestation) Children and pets are safer - ultrasonic repeller works with low frequency ultrasound, it's hard for humans to hear, An eco-friendly alternative to dangerous poisons and sprays , chemicals and traps, no foul smell and no carcass, highly effective against rodents and pests. Effective work - insect repellent works 24 hours a day, 7 days a week. Most customers can see results within 3 - 4 weeks. The repeller should be placed in a location where its noise will not be affected by walls and furniture. It is widely used in home, warehouse, office, garden, hotel, etc. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.