Genuine OEM Volkswagen self-locking bolt, part number N91145401. This fastener is specifically engineered to resist loosening caused by vibration, ensuring a permanent and secure connection for mounted components. It is used in the horn mounting assembly to maintain the correct orientation and electrical ground contact. Genuine OEM self-locking bolts are critical for applications where vibration is present, as they provide the necessary locking torque to prevent hardware failure and maintain consistent component performance.