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
