If you already have a fuse block gizmo connected to your battery....great! If not then I highly recommend attaching a 4 to 6 position fuse block to your battery and then using it for attaching to your accessories like an air horn. Attaching the air horn wiring diagram, use the one on the right side of the diagram as it works for connecting the two wires attached to your original horn/button. Don't cut your horn wires as depicted in the diagram....just unplug the wires from the horn terminals and reattach to the relay terminals, should be same size.