Single UHF coaxial connector on an external waterproof socket.  Comes with 3m of coax cable and connectors.  Drill a hole to put the coax through and stick socket onto the side of your motorhome or caravan with supplied double sided pad and/or screw to the side of your caravan or motorhome.  Enables you to connect an external aerial without having to route the coax cable through a window or door.