High-intensity discharge (HID) lamps are a type of electrical lamps which produce light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina tube.
HID automotive lamps are using the technology similar to the common vapor-filled street lamps. And HID lamps are also called xenon lamps , just refer to the gas inside the lamps. In a Simpler wordings, HID is the upgraded lighting kits from the original halogen bulbs, it's getting more popular this few years, as most of the new car models are all equipped with the HID Light Kits.
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Advantages for HID Lights :
HID lights generate a greater output of light compared to the original halogen bulbs, which can up to 3 times. And its light covers almost 70% of the road, so it's good for road safely as driver has a better vision on the road. If you have the experience in using the original halogen bulbs, the bulb life is always short, but HID lights can last up to 4-10 years with a greater durability, can withstand a greater amount of vibrations and shocks. HID light is a good choice when you are planning to upgrade your car headlight system, as it provides greater light with lesser power consumption, can save it up to 25%.
Color Temperature:
HID Color temperature refers to the degrees (K) , which simply the measures of the color for the lighting output, like golden yellow, white, crystal white, blue.
Degree (k) refers only to the color, while lumen refers to the lighting intensity. So the higher the color temperature (degrees K) doesn't mean a higher light intensity (lumen). Here is the summary for the common color temperature on the market -- 3000K (Golden Yellow) , 4300K (Bright White), 5000K (white), 6000K (Crystal White),8000K (Crystal Blue), 10000K (Aqua Blue), 12000K (Purple-Blue).
Bulb Size :
The common bulb size is H1, H3, H4, H7, h13, 9004, 9005, 9006, 9007, D1S, D2S. And it has single beam conversion, hi lo kits, Telescope and Bixenon kits.
Here is the summary for the features and bulb sizes ranges for all those kits.
Single Beam Conversion Kits -- H1, H3, H4-1, H7, 9004-1, 9005, 9006, 9007-1, with 2 ballasts and installation clamps.
Hi-lo Beam : H4-2, 9004-2. 9007-2 hid for low beam and halogen bulb for high beam, with 2 ballasts and installation clamps.
Telescope Kit : H4-3, 9004-3, 9007-3, single HID can switch between high beam and low beam, with 2 ballasts and installation clamps.
Bi-xenon Kit : H4-4, 9004-4, 9007-4, 2 HID bulbs on each bulb, which works for high and low beam, with 4 ballasts and installation clamps.
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More information and pictures for different color temperatures would be found on HID Conversion Kits