【Effective Ultrasonic for Most Dogs】 This dog bark control device is suitable for most breeds and sizes, but not for deaf or hard-of-hearing dogs. Some dogs may be afraid of or dislike the sound of ultrasonic waves, which is why they may not stop barking at first. Please wait up to 2 weeks before training. Safe and Effective Ultrasonic Bark Control: The sound is harmless to pets. If your dog is hard of hearing or aggressive, the bark control may not have the desired effect. It is not recommended to use an ultrasonic dog device against two or more dogs barking at the same time. 【Easy to Install and Waterproof Anti-Bark Device】 The anti-bark device is designed to be easily hung or mounted on a tree, wall, or fence post to discourage your dog or your neighbor's dog from barking. Make sure the ultrasonic bark control system is facing the dog in an open area. Product Description: The product is designed to resemble an alarm clock. The Deluxe Outdoor Ultrasonic Bark Control can be hung from