The microphone sensor of this deluxe outdoor ultrasonic bark control has an integrated microphone and thus triggers an ultrasonic sound when barking, which interrupts your dog’s barking. TIMER The digital timer of this ultrasonic bark control allows you to keep track of the day -or night time when the device should be active. 15 METERS RANGE The ultrasonic unit detects barking through the integrated microphone within 15 meters and emits a signal tone that can only be heard by dogs.< /p> DISCRETE BIRDHOUSE LOOK This ultrasonic bark control for outdoors is very discreet due to the unobtrusive birdhouse look and can also be used for neighboring dogs.