What is the interior part that covers the bolts for the outside mirrors called?

I recently put tweeters in my truck so I cut out a hole on the triangle shaped cover that goes over the back of the mirrors. This is referring to the drivers and passengers mirrors and not the rear view. The cover is in the interior and is a seperate part from the door panel. I drilled the hole to size and put the tweeter in but did not account for depth. The hole was not deep enough to put the tweeter in so I need to get replacement covers and find a new place to mount the tweeters. Thanks