1. 4 Modes Barking Control Devices The anti barking device has 4 adjustable ultrasonic volume levels. Turn the knob to test different frequency bands to get the effect. When the anti barking device is turned on, it can detect barking within 15, 30, and 50 feet respectively and automatically activate to emit ultrasonic waves to stop dog barking. 2. Anti Barking Device Our anti barking device for dogs indoor and outdoor is waterproof and can be used even in rainy days. It can be easily hung from a tree, fence post or anywhere with the included lanyard to effectively stop dog barking. 3. Auto Anti Barking Device Dog barking control devices have an excellent effect on stopping dog barking. The ultrasound emitted will correct the dog's bad behavior and automatically stop excessive, noisy dog barking, giving you a quiet life. 4. Suitable For MultiBreed Dogs Whether you have a small dog or a large dog, our no bark device is effective for most dogs, giving you peace of mind and creating a tranquil atmosphere in your home.