This is the Painless Performance main wiring loom that goes under the dashboard. Think of this as your Mustang's nerve center. All harnesses plug into the main wiring loom. Included is a modern, high-tech fuse box (with easy-to-replace fuses) that mounts in the same location as the factory fuse box. The harness plugs into all of your Mustang's switches to completely replace your Mustang's original wiring system.