Genuine OEM Volkswagen hexagon collar nut, part number N91130803. This self-locking nut is designed to provide a secure, vibration-resistant connection for mounting electronic control modules and their brackets. It is used in the ABS/ESC control module assembly. The nut features a durable, heat-treated steel construction with a protective coating. Using genuine OEM fasteners is critical for electronic module mounting to ensure proper grounding and to prevent hardware loosening due to vehicle vibrations.