Safe to use: Ultrasonic insect repellent is friendly to humans and pets, keeping away all kinds of small enemies, such as mice, rats, mosquitoes, flies, beetles, cockroaches, moths, ants, bed bugs, etc. Wide Coverage: The repellent can cover an area of up to 15-30 square meters. You should use one unit per room for best results, as ultrasonic waves cannot pass through walls or solid objects. Indoor spaces suitable for this kind of repeller plug-in ultrasound are houses, garages, offices, companies, restaurants, warehouses, etc. REA: This ultrasonic repellent is equipped with a dual microchip system and is suitable for areas ranging from 15 to 30 square meters. Since ultrasonic waves cannot penetrate walls and solid objects, it is recommended to place one in a room. Additional units are required for areas with severe pests. It is widely used in homes, warehouses, offices, gardens, hotels, etc. We recommend that you install one for each room, as ultrasonic waves cannot penetrate walls and solid objects. But for areas with severe infestation, we recommend installing 2 or more units in other rooms. If you install devices in one room, they won't work in other rooms. Ultrasonic insect repellent is chemical-free, non-toxic, low power consumption, silent and safe for people and pets, no need to clean up dead pests, no more calls to pest control technicians for help, no batteries required, saving a lot of money. Size: 50*50*43mm color: White Packing list: 2pcs