Genuine OEM Volkswagen hexagon bolt, part number N91126701. This long-reach fastener is designed for the secure mounting of the A/C compressor to the engine assembly. It is engineered to handle the specific vibration and load requirements of the compressor unit. Genuine OEM fasteners are critical for this application to ensure the compressor remains perfectly aligned, preventing belt misalignment and ensuring the longevity of the entire A/C system.