The PetSafe Elite Outdoor Bark Control can teach dogs of all sizes to be silent. Disguised as a birdhouse, this weatherproof device has an internal microphone that picks up the sound of barking, then sends an ultrasonic tone to correct your dog's noisy behavior. The ultrasonic tone is inaudible to most humans but is annoying to dogs. They'll quickly learn to associate their barking with the unpleasant sound. This unit can also control your neighbor's dog's barking if it's within the 1/4 acre hearing range. A built-in digital timer can automatically turn the unit on and off at specific times.