The Principle of Mosquito Repellent: the Bracelet Achieves the Effect of Repellent Mosquitoes by Imitating the Sounds of Female Mosquitoes, Such As the Sounds of Male Mosquitoes and Dragonflies. In Nature, the Bloodsucking Female Mosquitoes Are All at the Stage of Conception and Spawning. At This Price, Female Mosquitoes Will Prevent Male Mosquitoes and Avoid Secondary Conception. So the Sound of Male Mosquitoes Can Achieve Mosquito Repellent Effect.Product Features: Pure Physical Mosquito Repellent, Non Chemical Mosquito Repellent, Safer, Safer, More Environmentally Friendly, and Healthier. Can Be Worn by the Elderly, Children, Pregnant Women and Pets. The Product Can Be Worn Indoor and Outdoor (sea, Park, Camping, Climbing, Fishing)Specifications:Product Name: Ultrasonic Mosquito Watch;Function: Sonic Mosquito Repellent;Input: 5V / 0.5A;Output: 34Hz-70KHz;Battery Capacity: 80mAh;Charging Time: About 30 Minutes;Endurance Working Time: 150 Hours;Product Color: Black, White, Blue, Pink;Package Included:1 * Mosquito Repellent Bracelet1 * Charging Cable1 * User Manual