Genuine OEM Volkswagen Viscous Fan, part number 04L121301A. This fan is a critical component of the engine cooling system, designed to draw air through the radiator to maintain optimal engine operating temperature. It is located at the front of the engine, driven by the engine's accessory belt system. This viscous fan utilizes a temperature-sensitive clutch to engage and disengage, providing efficient cooling only when needed. Genuine OEM parts are vital for viscous fans to ensure the correct rotational speed, balance, and durability, preventing vibration and ensuring effective heat dissipation for engine longevity.