GoodLife Pro Ultrasonic Bark Control Training System Dog Silencer The world's first indoor and outdoor bark control device as well as the first anti-bark unit to operate electrically or with a single 9-volt battery Your dog silencer pro package includes a tiny keychain remote control - the only bark control device in the industry to include such a luxury Our humane training technique uses an age-old principle that teaches dogs to associate their barking with the irritating frequencies Both audible and ultrasonic frequency settings, with sound traveling up to 200 to 300-feet Installs anywhere with ease Includes mounting holes and fold-out feet