For panel installations to eliminate magnetic interference.
Brass with black oxide finish.
What you referring to is an instrument nut, sometimes referred to as a grasshopper nut and they come in different sizes. The thread size is the same, but the instrument bezel thickness can be different per gauge. They are ordered by the back bezel thickness. They are inserted from the back, and they have ears pointing out that slide into a groove between the front and back bezel to stay in place. A sample part number is MS33737-9C. A search on our web site for this part number will take you directly to the web page containing all the sizes.