Rick's Free Auto Repair Advice

HID headlight bulb

HID headlight bulb — what the letters and number mean

HID bulb designations

1st position: HID bulbs are “discharge” bulbs so the first letter is always a D.
2nd position: Designates the series; 1, 2, 3, or 4 (more on that later)
3rd position: “R” or “S” denotes whether the bulb is designed for use in a reflector style housing or a projector style housing. A bulb for a reflector style housing has an opaque shield that masks off a portion of the light to match a reflector style headlight’s optics. The “S” bulb does not have the shield.

HID D1R and D1S bulbs

D1R and D1S HID Bulbs have built in igniters to start the arc. If your vehicle requires a D1 bulb, it only has a ballast and the bulb. All D1 series bulbs contain mercury.


HID D2R and D2S bulbs

D2 series bulbs do not contain an integral igniter. These also contain mercury

D2R and S HID bulbs
HID D3R and D3S bulbs

HID D3 series bulbs do not contain mercury and include an integral igniter. However, they are NOT interchangeable with ballasts designed for D1 style bulbs.

D3R and D3S HID bulbs
HID D4R and D4S bulbs

D4 series bulbs require an external igniter like the earlier D2 style bulbs. They will Not fit into a D2 headlight.

D4R and D4S HID bulbs
©, 2022 Rick Muscoplat

Posted on by Rick Muscoplat


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