If you are thinking about upgrading your headlights, you have probably seen both "LED bulbs" and "Bi-LED projectors". They work very differently – here is a simple explanation.

What is a Bi-LED projector?

A Bi-LED projector is a headlight unit that uses LEDs as the light source together with a lens system to control and shape the beam. Bi means one unit does both low and high beam, using a mechanism such as a moving shield to switch between them.

How is it different from an LED bulb?

  • An LED bulb is only a light source. It replaces the original bulb, and the light comes out according to the shape of the original headlamp
  • A Bi-LED projector is a complete lighting system – light source, reflector or collector, lens and beam-control mechanism – so it can produce a designed beam pattern with a clear cut-off line

A well-designed, properly installed projector puts light where it is needed with a sharp cut-off that reduces glare for oncoming drivers. Real-world performance still depends on the projector's quality, the installation and the headlight aim.

Can a reflector headlamp be converted to a projector?

Many cars can take a retrofit projector inside the original headlamp, but the space inside, the mounting structure, the electrical system, safety and the relevant regulations all need checking. Most installs require opening the headlamp, so have an expert assess and fit it, and always re-aim the beam afterwards.

How to choose a projector

Lens size

Common sizes are 1.5, 2.0, 2.5 and 3.0 inches. It must fit the space inside your headlamp – bigger lenses need more room, so a technician measures first.

Power (watts), low/high

Specs are usually shown as a pair, e.g. 45W/55W for low/high. Watts measure power use, not brightness – the optics and beam distribution matter just as much.

Colour temperature

Usually around 5800–6000K (white). Some models offer 3 colours, popular for fog and auxiliary lights.

Number of reflectors

Some high-end units use several reflectors in one projector for finer light control.

ZETA projectors

  • Z1 2.5": 35W/45W, 5800–6000K, 1-year warranty
  • Z2 3.0": 45W/55W, 5800–6000K, 1-year warranty
  • Z3 2.5" (formerly GT3) and Z4 3.0" (formerly J1): 70W/80W, 3 reflectors, 2-year warranty
  • Matrix M5 1.5": 45W/55W, 6000K, 2 reflectors for tight headlamps, 2-year warranty
  • GW-1 (2.0") and GW-3 (3.0") projector fog lights for Toyota, white or 3-colour, 2-year warranty

All run on 9–16V. See details and prices in ZETA Projectors; installation parts in Projector Brackets and Headlamp Wiring Harnesses.