Designed to repair the thread for the glow plug threads. Tap Size: M8 x 1.0, M10 x 1.0, M10 x 1.25, M12 x 1.0, M12 x 1.25, M14 x 1.25. Thread coil size: M8 x 1.0(I) - M10 x 1.0(E) M10 x 1.0(I) - M12 x 1.0(E) M10 x 1.25(I) - M12 x 1.25(E) M12 x 1.25(I) - M14 x 1.25(E).