One part is the socket the other is a template to use if your going to make your own out of metal. I would advise against plasma cutting. Keep in mind sizes are made to print. Which include plastic shrinkage, because the pool is cold after all.

The socket has a left hand thread 5/8-11 hold with taper. Thread and taper is about .75" long because that was the what I had and what I could easily cut it down to.