Genuine OEM Volkswagen Door Window Guide Rail, part number 11E839439L5AP. This component is installed along the upper and side edges of the door window opening, providing a smooth channel for the window glass to travel. It ensures stable movement and helps seal the window when closed. The guide rail is finished in black (5AP). Using a genuine OEM guide rail is crucial for proper window function, preventing binding, excessive wear on the window motor, and maintaining effective sealing against external elements.