It's a kit with a "special" tap. 1st you have to drill out the hole to clear the old threads 2nd you use the "special" tap to cut new threads. The Heli coil itself looks kinda like a spring that threads into the new threads you cut. But on the inside of it it is the correct threads for the threads you had to repair. It's almost like a resleeve for threads. (The reason for the special tap is it is the same thread as the thread you are fixing but at a thicker diameter to allow the heli coil to thread)