Check the listing for details. 7-Way Trailer Plug Holder Mount – 3D Printed RV Camper Truck Socket Dock. Condition: New. Listed at 11.99 USD. This 3D Printed 7-Way Trailer Plug Holder is designed to securely hold standard RV-style 7-way blade plugs when not in use. No more dragging cords, dirt-filled connectors, or plugs hanging loose from your hitch.