Heli-Coil has the most effective and universally accepted method of thread repair. Heli-Coil inserts quickly and permanently restores stripped, worn or damaged threads to their original size and condition. Inserts work in any part of material; aluminum, magnesium, cast iron, bronze, etc. The use of light weight materials in fuel efficient cars means more thread damage..there is a Heli-Coil insert to repair virtually every application. Restore parts that otherwise would have to be scrapped.Inch Fine Thread Repair Kit - Thread Size 5/8-18 x .938 LengthTap Part No. - 821-10Installation Tool Part No. - 2299-10Tool Type - 3Insert Package Part No. - R1191-10Drill Size - 41/64" (Drill bit not included.)6 Inserts Per Kit