Re: Ludwig's new Signet 105 drum line!
Ok, the piece that you are talking about is a simple plastic plug that is installed in the lug to aesthetically conceal a hole.
What is so mysterious about it?
Many products have similar concealment plugs.
Your car probably has at least 12 of them. Look closely at your cars door panels and you will probably find a few by the armrest and the interior door latch release.
Some are round and some are square or rectangle in shape. They hide access to fasteners that are necessary to the function of the door.
I kind of like old drums:)