HID (High Intensity Discharge) refers to lighting technology that relies on an electrical charge to ignite xenon gas contained in a sealed bulb. A normal halogen bulb uses a filament which can burn out in as little as 200 hours. HID bulbs are gas filled capsules that are rated for a lifespan of nearly 4500 hours. HID bulbs also shine much brighter due to this technology. Unlike halogen bulbs, HID's emit a type of light that closely resembles natural daylight and is therefore easier on human eyes. In fact, HID lights are currently used in most sports arenas, stadiums, and train stations worldwide. Don't be fooled by lower end Xenon replica bulbs sold at most retail shops. They are no match for the intensity, purity, and efficiency of high intensity discharge headlights. NOTE: Make sure the Bulb Size and Color Temperature suitable for your car !