PetsN'all Upgraded Ultrasonic Outdoor Dog Bark Controller in Anti-Bark Training Birdhouse Shape BARK CONTROL: Uses ultrasonic technology to irritate dogs and discourage them from barking AUTOMATIC SENSOR: Sensitive microphone isolates and picks up barking up to 50 feet away to activate the device FOUR SETTINGS: Four adjustable ultrasonic volume levels test, low, medium, and high  with LED battery power level indicator HUMANE: Safe and humane method of bark control suitable for all breeds and sizes of dogs EASY INSTALLATION: Pre-assembled, easy set-up, requires low maintenance, and weatherproof (but avoid exposing to very cold or very hot temperatures from 0C~45C, 32F~113F). Attractive and discreet birdhouse design looks great in your home or yard