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Fitment & Identification

HID bulbs come in a variety of fitments and applications. Every bulb style or fitment has identification characteristics built in.

D2S, a very common OEM bulb fitment, stands for Discharge 2nd-Generation Shielded.

D2H & D2S Bulbs w/D2S Socket

To further break that down, Discharge means High Intensity Discharge, 2nd Generation means it’s the 2nd version and shielded means it’s for a projector (as a cutoff shield will control the light pattern & output).

D2R stands for Discharge, 2nd-Generation, Reflector. This type of bulb is found on a factory equipped HID vehicle utilizing a reflector for it’s light output & control. While this may be DOT approved it does not provide the precise control & output of an HID projector unit.

D2C is an aftermarket based bulb created for tight fitting applications.

D2S, D2R & D2C all share common bases, their cutout or or notch marks are positioned differently.D2 Bulbs Chart

D4S is another newer style HID bulb. It’s a 4th generation version of a D2S bulb that uses no mercury in it’s chemical compounds.

D1S Bulb

D1S is the 1st generation of shielded or projector based HID bulbs.

Fitment of OEM HID D2S bulbs into a halogen housing requires modifying the HID bulb or using an adapter.This is generally not recommended.

HID Bulbs AMP Style

Aftermarket HID bulbs generally have fitments associated with Halogen bulbs: such as H7, H11 or 9005. These bulbs are NOT OEM specification but do have similar characteristics. They are usually associated with kits with aftermarket ballasts & wiring. They can also be associated with certain HID designed projectors, such as the Mini Morimoto MH1 (which uses an H1 based HID bulb).

What about hi/low or bi-xenon bulbs?

The term “bi-xenon” does refer to the high and low beam functions of a headlight (or in this scenario an HID setup). However, “bi-xenon bulbs” are never a good idea as they are not designed to disperse or control light correctly in any headlight application. Please note: Bi-xenon bulbs are VERY different from a bi-xenon projector. See bi-xenon projectors here.Bi-Xenon Bulb

A bi-xenon bulb is an HID bulb that has moving parts (generally a switcher/solenoid motor). When the user clicks their high beams on, the bi-xenon bulb shifts it’s position by either pushing or pulling the HID capsule. This changes the light output point, which changes where you see the light on the road ahead of you. The reason bi-xenon bulbs are never recommended is that their point of focus is already incorrect (they are aftermarket bulbs commonly used in halogen hi/low reflector housings). Shifting the capsule further out of alignment shifts and /or creates even more glare.

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