Abstract: A plug for impeding transmission through an aperture defined by an edge in a panel. The plug is substantially elastic, and has a central portion and a peripheral portion attached to the central portion by one or more bridge portions. The central portion and the peripheral portion are separated from each other along two or more cuts. Also, the central portion includes a middle part and two or more flap parts extending from the middle part, the flap parts being defined by the cuts. The flap parts are positioned to grip the edge after the flap parts have been deformed and released in the aperture.