100% Safe and Humane: Our high quality ultrasound is safe for humans and other animals as people over 20KHZ cannot hear it. Say goodbye to irritating and dangerous chemicals. This type of microelectronic technology produces no radiation and is silent. Safe for pregnant women and babies Highly effective coverage: The effective range of the product is about 80-120 square meters, and the best effect is about 50 square meters. This 20~55KHZ ultrasonic can drive away unwanted pests without killing them. Ultrasonic frequencies cannot penetrate walls, so one unit per room, unless you are severely infected, you may need more. Easy to use: just plug in a outlet and let the magic happen. Be sure to insert the ultrasonic pest control insecticide at least 80cm from the ground. An ultrasonic insect repellent can take 3-4 weeks to work. Please note that if you have rodents in your home, such as hamsters, guinea pigs, etc., please be careful. Please ignore it. Endless Places of Use: You can use them in many places. For many reasons, this ultrasonic insect repellent can help you repel all pests. It is very suitable for living rooms, bedrooms, bathrooms, kitchens, offices, garages, warehouses, gardens, etc. Notes: 1. If you have hamsters in your home, please stay away or don't use this insect repellent. 2. It should be installed at a distance of 31 to 47 inches from the ground and perpendicular to the ground. 3. Carpets, curtains, refrigerators and any other furniture that can block or tune frequencies should be avoided. 4. It is normal for the pests to increase during the first days of use, because it means that they will leave their place of life after being attacked by the ultrasound. 5. This ultrasonic insect repellent is very effective after 15-20 days, please be patient. 6. Ultrasonic waves cannot penetrate solids and walls, so for best results, one unit per room, multiple units with larger surface area. Product Size: 9cm x 5.6cm x 5cm. Shipping Quantity: 4 pieces.