Genuine OEM Volkswagen hexagon collar nut, part number N91130802. This self-locking nut is designed to provide a secure, vibration-resistant connection for exhaust system components. It is used in the exhaust assembly to ensure airtight seals at mounting points. The nut features a durable, heat-treated steel construction with a protective coating. Using genuine OEM fasteners is critical for exhaust systems to withstand extreme thermal cycling and prevent leaks or hardware loosening over time.