These brass electric receptacle floor covers (single and double) formerly had a paper "gasket" between the back of the cover and the receptacle. I think "GASKET" is the word you are looking for. These gaskets were formerly a black tar-paper like material and were changed to a foam material in the late 60's or early 70's, if my memory hasn't slipped too far. They were meant to try to keep out water/wax/shampoo, depending on the floor surface, when these floors were being cleaned. Thanks, John Walsh
