This anti-barking device is New. Safe For Dogs And People: The anti barking device for dogs is safe and effective for dogs of all types and sizes (10-130 lbs).for dogs 6 months to 8 years old.most humane and used widely way to keep your own dog or you neighbors dog from barking. Upgraded Design: Anti barking device uses the latest ultrasonic technology, it will automatically sense the sound of the dog barking and automatically emit sound waves that only the dog can hear, once the dog stops barking, the anti barking device for dos will stop emitting ultrasonic waves, which will help to correct the dog's barking habit. Rainy Days& Durable: dog bark deterrent devices come with a well-designed cute shape.hang the bark box in a tree, on a fence post or anywhere. Stop dog barking device can work even on windy and rainy days. 4 Levels Of Stop Barking Devices: dog barking silencer with 4 adjustable ultrasonic volume levels - test, low, medium, and high,please turn the knob to test.