RETHREADING FILE RESTORING SIZE 11 12 13 14 16 18 20 AND 24 TPI - in.NU-THREADin. RESTORING RETHREADING FILE. RESTORE DAMAGED THREADS THAT ARE BENT RUSTED OR CROSS THREAD. FOR USE ON SCREWS BOLTS STUDS PIPE AND PIPE FITTINGS. CAN BE USED AS A PITCH GAUGE. OXIDE COATED TO PREVENT CORROSION.