Abstract: A first resilient wall having an opening to the outer diameter of the wall for a line through the first wall is squeezed by a second wall having an opening for a line through the second wall, and a third wall and insert. The insert is nested in the third wall. The third wall and insert form between them an opening for passing a line between them, the opening in the third wall being large enough to pass through a termination of the line that is larger in diameter than the line. Material of the squeezed first wall is displaced against the line and against an inner wall of a hole in which the plug is mounted.