Genuine OEM VAG Belt Pulley, part number 079903119J. This pulley is part of the alternator assembly and is responsible for driving the accessory belt. It features a freewheel mechanism, also known as an overrunning alternator pulley (OAP), which allows the alternator rotor to continue spinning for a short time after the engine is shut off, reducing stress on the belt and tensioner. Genuine OEM parts ensure correct fitment and optimal performance of the charging system.