Commercial Electric 81965 Installation guide

I have reviewed the product details for the 81965 Hex Nuts from Commercial Electric. This document provides brief information about the product, including its 1/8-IP threading, solid brass construction and its intended use in lighting fixtures. I'm ready to answer your questions about this product.
What is the thread size of these hex nuts?

Are these hex nuts suitable for lighting fixture?

What material are these hex nuts made of?