One of brand new xenon headlight HID bulb ballast.
Audi part number: 8E0-907-391-B.
Fits xenon headlights of:
2007-2009 Audi A4, S4, RS4 Cabrio (without Curve lighting)
2006-2009 Audi A4, S4 sedan and wagon (without Curve lighting)
These are not OEM parts.