Your dog will no longer have to bark, whine or scratch at the door to let you know when he/she needs to go outside. Eliminate accidents in the house by giving them a way to communicate to you that they need to go.* Training is fast and easy.* Works with dogs of all ages and sizes.* Comes with easy-to-follow training instructions.* Fits over most door knobs or handles (or can be placed on a hook by the door).