Electronic repellent device is a new type of high-tech electronic products, it uses high-frequency ultrasonic sweep circuit, resulting in the 22 ~ 55KHZ Ultrasonic Sweep, scientific research found that the mosquito, cockroach, rats and other pests in the scope of sound waves of this frequency, their physiological functions and endocrine system will be disordered in order to drive and kill off them, the effects of ultrasound on human and other animals are harmless, because people can not hear the sound waves more than 20KHZ.