Reverse Action Spark Plug Thread Chaser 12mm

• Specially designed to repair damaged spark plug threads on modern petrol engines. • Unique design allows the tool to be passed through the plug thread into the combustion chamber, then expanded to the correct size starting on the inner, undamaged threads. • Traditional thread restorers rely on luck for the restored and undamaged threads to align. • The first letter(s) of a Denso, NGK and Bosch plug code is the thread size identification. For Champion brand the second letter(s) of a plug code is the thread size identification.