Ultrasonic outdoor bark control unit looks like an ordinary birdhouse that can hang in a tree, on a fence post, or anywhere outside. It can detect barking up to 50 away and has 3 range settings. Whenever your dog, or your neighbors, barks, he/she will hear a safe, high-pitched sound (audible to humans) that will teach him to stop the annoying habit. Maximum range up to 50, 4 levels of operation including a test mode, durable, and weather proof, low-color LED for good/low-battery indication, uses a 9V alkaline battery (not included).