Genuine OEM Volkswagen breather, part number 0AZ409831. This component functions as a pressure relief valve for the drivetrain assembly, allowing for the expansion and contraction of air within the housing. It is located on the upper casing of the unit as indicated in the technical diagram. Genuine OEM parts are engineered to provide the exact flow rate and filtration properties necessary to keep internal components free from moisture and debris, ensuring a long and reliable service life.