PetSafe's® Outdoor Elite Bark Control resembles a birdhouse to look right at home in your backyard. A small microphone detects when a dog barks and produces an unpleasant ultrasonic sound that only the dog can hear. After a few barks, the dog will begin associating the sound with barking. A timer can be programmed so the unit turns on and off at specified times. Can be hung from a tree or set on a table. Uses one 9-volt battery (not included). Imported.