GTXT Noob

Sorry to bring back this thread. So I'm going to be doing the passenger side valve cover gasket in the near future. I see a felpro gasket set with the "valve cover gasket and the inner gasket/sparkplug gaskets." I also know I will need the half moon seals. But on Advance Auto Parts, Felpro also has this circular plug part that's listed for the valve cover?? What is this? Do I need this? Below is a picture of the circular plug I am referring to. The link to the circular plug I'm looking at is here... https://shop.advanceautoparts.com/p/felpro-circular-plug-es-72418/10942906-P?searchTerm=valve+cover+gasket And is permatex ultra grey or ultra black better?