What Do I Need – Cage Whip Mount

I have a new after market cage. There is a female threaded tube welded on the upper rear of the cage. Pretty sure it is for a whip, but I don’t know what the piece is called that will thread into there. Builder told me it is 1/2" thread, but will need to go to ACE to confirm.

Anyone know where to find these connectors?

In the photo below it is right above the rope.