Genuine OEM Volkswagen Door Window Guide Rail, part number 5NN837431B5AP. This component is crucial for guiding the door window smoothly up and down, and often contributes to the window's seal against the elements. It is positioned along the upper frame of the door, where the window glass slides. The guide rail features a black (5AP) finish and weighs approximately 1.859 kg. Choosing a genuine OEM window guide rail ensures precise dimensions, correct material properties for friction and sealing, and long-term reliable operation of the power window system.