Ballast headlight control unit, clear and bright light can help you identify the road ahead and obstacles more clearly, improving driving safety The headlight control module, or HID power regulator, provides the voltage required to activate the headlights and regulates the current to the headlights once they are illuminated W003T23171 63117318327 7318327 D1S Xenon headlight ballast Function: automatic ballast, current controllable, output disconnection protection function. Features: Automotive ballast, power saving, constant power output design, extended service life., Manufacturer: YUNLL