“Do I have dual-beam or single-beam headlight bulbs?” The answer to the question often brings confusion, but it’s surprisingly simple:
The term “Dual” and “Single” refer the function of a headlight bulb. A dual-beam headlight bulb has dual functions; The bulb creates a low and a high beam – “dual beams” in one headlight bulb. A single-beam headlight bulb has a single function; the one bulb creates only one beam
Single Beam Headlight Bulbs have one single filament inside the bulb which produces a single beam pattern: either high beam or low beam.
Since a single beam headlight bulb can only create a single beam pattern, one bulb is needed for a high beam bulb and a second bulb is needed for a low beam bulb.
Just remember if you’re looking at an LED headlight bulb or HID conversion kit and you’re unsure of the difference, just remember to focus on the bulbs themselves, not the headlight housing. Do you have a bulb that does 2 beams in 1 bulb or 1 beam in 1 bulb?