The short wire is double ended to offer a straight boot and a 90-degree boot on one tool
Connect the tool between the spark plug and the plug wire. The short wire is double ended to offer a straight boot and a 90-degree boot on one tool. With the engine running, the tool flashes a mirrorimage of the ignition spark. The additional 7" extension plug wire is used on coil-on-plugs that are recessed and hard-to-reach.
