Suitable for dogs of all sizes. Uses high frequency sounds to reduce excessive barking in in-ear dogs, suitable for dogs 6 months and older, up to 25 feet long. Designed to easily hang or mount on a tree, wall, or fence post to stop your own dog or your neighbor’s dog from barking. Sensitive microphones are included to isolate and pick up barking up to 50 feet away to stop barking outside and inside). Note: Not suitable for deaf or hard of hearing dogs. Like an alarm clock, small and easy to place and hide, two LED battery status indicators, four adjustable ultrasonic volume levels, test the low, mid and high ranges. Durable and waterproof, the outdoor ultrasonic barker features a power indicator. It can be set to off to protect the battery when you are away. Outdoor ultrasonic barking device designed for outdoor use