The Bark Stop PRO is the industry's most advanced outdoor animal/ pests deterrent / repellent product. It uses ultrasonic technology as well as sonic alarm to repel animals/ pests from your garden, yard or outdoor area, etc. The device is environmentally friendly, safe for humans and pets, and won't even harm the animal/ pests you want to repel. The ultrasonic technology provide two effective functions in one device: a) Dog Silencer: The ultrasonic is safe for your dog and provides a consistent message to put an end to nuisance barking; b) Ultrasonic Pests/ Animals Repeller: The device is safe for humans and pets and a humane way to repel pests/ animals.