FOR DOGS OF ANY SIZE - uses high-frequency sound that works to reduce excessive bark of dogs within hearing range; for dogs 6 months and older UP TO 25 FOOT RANGE. Contain sensitive microphone isolates and picks up barking up to 50 feet away to stop barking both outdoors and indoors (recommended starting mode for indoors is level 1, increase if needed). NOTE: Does not work on deaf or hearing impaired dogs. Like an alarm clock, small and easy to place and , Two LED battery status indicator, four adjustable ultrasonic volume levels-test low range, medium range, and high range. Durable and waterproof,The outdoor ultrasonic barking device has a power indicator. When you leave, can be set to "Off" to the battery.Designed for outdoor use, outdoor ultrasonic barking device. 100% safe, humane and professional way to train your dog to stop barking. Designed for easy hanging or mounting on a tree,wall or fence to keep your own dog or your neighbors dog from barking.