The Sealey Reverse Action Spark Plug Thread Chaser M12 (Model No. MS002) is specifically designed for repairing M12 threaded spark plug holes commonly found in many modern petrol engines. This thread size is widely used across various manufacturers, making this an essential tool for professional workshops and serious DIY mechanics. The M12 variant features the innovative reverse action mechanism that allows the tool to pass through the damaged plug thread into the combustion chamber, then expand to engage with the inner, undamaged threads. This approach ensures proper alignment from the start, eliminating the hit-and-miss results associated with traditional thread restoration tools. To identify the correct thread size for your application, simply check your spark plug code: for Denso, NGK and Bosch plugs, the first letter(s) indicates thread size, whilst Champion brand uses the second letter(s) for thread size identification. Features and Benefits:M12 thread size for broad engine co