Ruuf Indoor/Outdoor Ultrasonic Dog Bark Deterrent Barking Control Bird House Shape Control Barking by Ultrasonic Sound: Stop barking dogs by ultrasonic sound. Please kindly note the device is not work on deaf or hearing impaired dogs Built-in Microphone & Detect Barks Distance: From 15 to 50 feet away with the use of an built-in microphone 4 Modes: 3 normal modes and 1 test mode Battery Need: Powered by 1 * 9V battery (Battery is not included in package) Warranty: Purchase with confidence, it comes with a manufacturer lifetime warranty for 24 months