Vintage Original NCR National Cash Register Clock securing Screw/knob?

Description

This is an vintage original National Cash Register Co. Knob/Screw that, if I remember correctly, is used for securing a clock to your register. I must admit that I am not entirely sure that is the correct though. If it is correct then here is your chance to get a really tough screw to locate. You be the judge.
It is constructed of nickel plated red brass/bronze. The plating is in fairly good original condition.
This measures 11/16" long from the outside of the knob to the end of the screw. The diameter of the knob is 1/2".
This item is being sold as is with no warranty or returns being offered.
I gladly combine shipping to save you money whenever possible.