Genuine OEM Volkswagen Dodecagonal Head Bolt, part number N91174801. This specialized twelve-point fastener is engineered for high-torque applications within the exhaust system. It is primarily used to secure the catalytic converter or manifold components, as shown at position 8 in the assembly diagram. The dodecagonal head design allows for superior grip and torque distribution in the confined spaces of the engine bay. Genuine OEM bolts are specifically heat-treated to withstand extreme thermal cycling without loosening or snapping, ensuring a long-lasting, leak-free exhaust seal.