[Working Principle] - When the product's microphone detects a barking dog, the product automatically emits a high-pitched ultrasonic wave. This ultrasonic wave is inaudible to the human ear, but can be heard by dogs. For dogs, this creates a shrill sound, causing the dog to stop barking and move away. 【Product Design】-- The product is designed for outdoor use. Its appearance is designed like a birdhouse. It can be easily hung on a tree, anywhere in your house or garden. It can be hung as desired, or placed on a table or anywhere else. [Product Features] - The product can prevent excessive dog barking from disturbing you and your neighbors. The outdoor ultrasonic anti-bark stopper can effectively prevent dog barking and does not require a receiving collar. Safe and effective, suitable for dogs of all breeds and sizes. [Precautions] – Ultrasound only allows the dog to hear what causes discomfort, and there is no significant punishment. The dog will get used to the product after hearing