Hand tool used to restore up to 60% damaged threads on internal threaded parts. Comes with special hardened HSS tool steel blade. The cutting blade is extended or retracted by rotating the serrated knob. After retracting the blade and inserting the tool; the knob is rotated to extend the cutter into an undamaged part of the threads. Automatically adjusts to the thread pitch since the blade is guided by chasing undamaged sections of the threads. The yellow nylon is used to counteract the forces of the cutting blade and prevent rubbing damage to the internal threads. Compatible with M8 to M11 or 5/16" to 7/16" diameter threads. - Auto guided by existing threads - Removes rust and burrs - Automatically chases good threads to repair / re-groove damaged sections - Hand tool - Hardened HSS tool steel cutting blades - For any thread diameter; inch or metric from M8 to M11 or 5/16" to 7/16" - For any pitch - For right or left-hand threads