The Bird-X Pest-X Plug-In Pest Repeller is an easy-to-use, easy-to-forget plug-in pest control device. Just plug it in; it effectively chases away pests in home or office. Includes 4 units, each covers 500 square ft. (clear space). Repeller is effective on rodent pests like mice and also insects like spiders, ants and cockroaches Safe for use around children and pets No poisons, chemicals or traps Use anywhere pests are seen Ideal for basements, garages, attics, crawl spaces, barns, sheds Covers average size rooms; use more units for large spaces or in rooms with a lot of furniture 4 units per 4 pk. Uses ultrasonic, silent technology Commercial technology superior to every other brand #1 bestseller Inexpensive, effective solution Safe around humans and pets 500 sq. ft. coverage per unit