BMW Genuine Bi-Xenon Light Headlight Head Lamp Left

Xenon headlights offer many advantages over halogen ones: based on noble gas, they provide a much brighter light with less energy consumption and last longer than conventional headlamps.
In addition to the normal xenon lights, BMW now offers xenon light for full and dipped beam headlights, known asbi-xenonheadlights. The light for the full beam headlights uses the same light source as the xenon dipped beam headlights: as soon as the driver turns the full beam on, by touching the lever on the steering column, the bi-xenon system folds away a screen located in the path of the ellipsoid-technology xenon headlights beam.

Represented by part number 1 in the diagram.