This Radio Mat Extra Transmitter Pad works with any Humane Contain Radio Receiver Collar to keep your dog out of restricted areas such as trash cans, furniture or even an entire room when placed by the doorway. When your dog steps on the pad, it emits a coded radio signal that triggers the stimulus on your dog's collar. It also gives you optional sound blast mode to reinforce the collar's shock stimulus. Place as many extra pads as you wish, anywhere your dog is not allowed to go.