Pet Dog Ultrasonic Barking Control Device Bark Control Outdoor Anti Bark Dog Barking Sonic Deterrent Muffler Stop Barking feature: Ultrasonic anti-barking device automatically detects barking up to 15m / 50 feet away. The bark control automatically emits high-pitched sounds that only dogs can hear. The ultrasonic bark control automatically stops emitting ultrasonic waves once the dog stops barking Ultrasonic frequencies are harmless to pets and completely inaudible to human ears, so you can use this device safely Can be hung on trees, indoor, outdoor walls or fence posts to deter any dog barking (within range). When the luxury outdoor ultrasonic barking alarm clock detects excessive barking, the microphone responds to the barking and activates the component It requires a 9 V battery - (battery not included). The outdoor ultrasonic sounder has a power indicator light. It can be set to "off" to protect the battery when you are away. Outdoor ultrasonic barking unit designed for outdoor use.