The Indoor Bark Control automatically deters your dog’s barking, bringing peace and quiet to your home. Using the adhesive-backed hooks, simply place one of the devices on a wall, door frame, or table in whichever room your dog barks the most. Whenever your dog barks, the device emits an unpleasant ultrasonic tone that's inaudible to most humans. Your dog will learn to associate his barking with the high-pitched sound and stop barking. Most dogs bark less within a few days. The deterrents are available in single or dual packs for homes to cover multiple rooms.