These pillar ball nuts are made using 6061-t6 aluminum. A natural finish.
the kit comes with delrin bushiung to give you a set and forget fit.
The nuts are designed to allow you a very easy start to avoid cross threading.
The nuts will screw about 3/4 in and then start to trighten up. As it gets close the the bottom it will snug down so the nuts will not back out.