The CEQUENT TRAILER PRODUCTS 4 Flat Trailer Connector Dust Cover / Rubber Plug is designed to protect a standard 4-flat trailer wiring connector when it is not connected to a tow vehicle. Made from flexible rubber, the cover helps keep dust, dirt, moisture, and other contaminants away from the connector and electrical contacts. Its simple plug-on design provides convenient protection and helps maintain reliable connector performance while extending the service life of the trailer wiring connection.