Compatible with 5 series (E60) 2003 2004 2005 ; for 7 series (E65 E66 E67 E68) 2002 2003 2004 ; for X5 (E53) 2004 2005 2006 ; for Z4 (E85 E86) 2003 2004 2005 2006 2007 Material: Xenon H-ID headlight ballast control unit module has passed extensive quality and reliability performance testing and is made of special materials to ensure stable performance and long service time. Function: H-ID ballast is important because it helps start the lamp and allows current to flow through the bulb, thus keeping the light on. Another important function is to control the current flowing through the bulb. Quality: Made of materials that meet strict OEM requirements, this product offers stable performance and is an ideal replacement option. Note: To ensure you receive the correct item, please confirm that your OEM number matches the one in the description.