1.If you're considering a non-chemical approach to pest reject, we recommend the Ultrasonic Pest Repellers are devices that emit a consistent noise at a frequency that is too high for humans to hear. These sound waves are designed to distract, annoy, and deter common household pests such as roach, spiders, mosquitoes, ants and rodents. Intelligent multi-frequency ultrasonic conversion systems make pests nowhere to hide.2.Pest repellents are simple to use. All you do is plug pest repellent ultrasonic in an electrical outlet, the repeller should be placed in a location where its noise will not be affected by walls and furniture. It is recommended to install this pest repeller between 30-50 inches away from the floor for flying pests and 10-30 inches from the ground for crawling pests.3.Since ultrasonic sound can not penetrate walls and solid objects, ONE ROOM ONE UNIT IS RECOMMENDED. 360 degree protect your home with no dead zone. It's widely used in homes, warehouses, offices, restaurants, supermarkets, hospitals, granary, etc.4.Ultrasonic insect repellent night light, in addition to being able to drive away pests in a healthy and environmentally friendly way, is also a small night light that can light up at night. There are two levels of brightness that can be switched.5.It usually takes 3-4 weeks for a different result depending on the amount of infestation.