When the microphone picks up the sound of your dog's bark, the 

PetSafe Indoor Bark Control emits an ultrasonic tone that can be

heard by your dog, but is silent to most humans.  Startled by the

high-pitched tone, the dog should stop barking, as it will associate

its bark with this unpleasant noise.

System includes:

*Indoor Bark Control Unit

*Adhesive-backed hook & loop fasteners

*2 - 3-volt CR2032 batteries

*Operating guide

*One year warranty

Works with most dog breeds and sizes

Not recommended for outdoors