This add-on part for the PortablePET Pet Partition makes it one rung taller, allowing you to extend it for use within a larger space. It keeps other cargo in a separate area at the back of the vehicle. The PortablePET Pet Partition (sold separately) is an adjustable fence-like space barrier that keeps pets, suitcases, and other cargo in a separate area at the back of the vehicle, where they belong. Driving a vehicle with pets can be dangerous. When travelling with your dog, keep your pet from exploring the rest of your car. This large, adjustable size is made especially for dogs.