.7-3MM TPI Thead Restoring File ~ Suitable for pitches .75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.5, & 3mm. ~ Restores damaged or rusted external threads on bolts, threaded shafts, pipes and pipe fittings. ~ The profile shape is square. ~ Overall length is 8-1/2″. ~ Sizes are clearly marked.