This lead is designed to help secure your dog to the seat so they don'r run as soon as you open the door.
It is adjustable to allow dog to move and roam without being to contrictive.
Easy to attach, either use the snap buckle through the seat belt buckle loop, or use the buckle slide (may not work on all back seat models, but will for almost all front seat ones).
There is a bungee cord inline that helps reduce jerking your pet during start and stopping