Pet Door Doorbell can be an invaluable aid and must have for busy homes. Find your pet scratching, whining, and barking when your best friend needs to visit the backyard. Or do you wait impatiently for your dog to return from the backyard so you can continue on with your business. Pet Door Doorbell will eliminate anymore hassles. A Pet Door Doorbell comes equipped with a key to fit on the collar. This key triggers to Pet Door Doorbell when your dog is within 3 feet of the door, inside or outside, and emits an audible tone for you to know your pet is at the door. As you can see getting a Pet Door Doorbell is a great way to make your life as a pet owner a little bit easier.