KATO Perma-Plug Kit is a professional spark plug thread repair kit that provides everything youÃll need to quickly and easily repair worn or stripped spark plug threads. Perma-Plug works in aluminum and cast iron assemblies and provides a positive locking system. Perma-Plug requires no drilling, simply tap the hole with the included piloted tap tool. The Perma-Plug kit includes three insert lengths to accommodate all applications. With Perma-Plug the repaired threads are better than new, and the assembly is stronger than the original! Perma-Plug Kit can be used with taper seat or gasket type spark plugs.