1.[ 100% Safe Control Device ] - Ultrasonic frequency is harmless to pets and has no effect on human ears. Harmless and humane way to keep your dog and your neighbors dog from barking Effective on all breeds & all dog sizes. 2.[ How Dose It Work ] - With the aid of an internal microphone which picks up dog bark, dog bark device is automatically activated when it detects barks. Then it emits ultrasonic sound to silence the dog. When the dog stops barking the ultrasonic sound also stops. 3.[ 4 Adjustable Sensitivity ] - Anti barking device has 3 range levels and a test mode. Including: Low Sensitivity(15 feet), Medium Sensitivity(30 feet), High Sensitivity(50 feet). 4.[ Waterproof and Durable ] - Ultrasonic anti-smashing, durable, weatherproof, sturdy dog skin control, lightweight, waterproof material, safe for indoor and outdoor use in any weather conditions. 5.[ Mini Design ] - This ultrasonic anti barking controller comes with a well-designed mini shape, can be hung on a tree, indoor, outdoor wall or fence post to stop any dogs barking(within range)