Xenon HID bulbs - SODIAL(R) 2x XENON HID REPLACEMENT BULBS LAMP 9006/HB4 35W 10000K 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 4,500 hoursHID bulbs also shine much brighter due to this technologyUnlike 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.