Ultrasonic insect repellent, safe and non-toxic no residue Physical insect repellent principle: through high-frequency ultrasonic interference with the nervous system of insects, to repel cockroaches, flies, mosquitoes and other pests, without the use of chemicals, non-toxic and odourless, mothers, babies and pets families feel at ease to use. Silent operation design: ultrasonic frequency beyond the range of human ear hearing, almost no sound when running, night use does not affect sleep. Multi-pest universal, one machine covers the whole house Composite frequency technology: for cockroaches, flies, mosquitoes and other different pest characteristics, release multi-frequency ultrasonic waves, repelling pests more efficiently, avoiding a single frequency resulting in pest adaptation. 360whole-house coverage: the effective range of a single device is about 80-120 square metres, and the 4-box set can cover large households or be scattered and placed in the kitchen, bathroom, bedroom and other key areas. Intelligent power saving, long life USB/plug-in dual mode: support USB charging treasure power supply or direct plug-in use, flexible to adapt to different scenarios. Low power consumption design: the average daily power consumption of a single device is only about 0.02 degrees, energy-saving and environmentally friendly, all year round use without burden. 4-box value set, more cost-effective protection for the whole family Multi-scene coverage: one unit in the kitchen, bathroom, living room and bedroom, forming a protective net to repel insects, and bid farewell to pests. Cost-effective choice: the price of 4 boxes is lower than the total price of 4 purchases of a single box, which is suitable for stocking up or gifting to friends and relatives.