These are available in both LHD (right hand traffic) and RHD (left hand traffic).
A link for where to buy these projectors new is near the bottom of the page.
OK, we need to break it down into 2 parts. Xenon means HID (High Intensity Discharge) headlights. These create a crisp bright light output with less heat and use less power than the standard 55w headlights. These are the sort of bright white lights you see on more expensive cars. They really light the road a lot better than halogen bulbs.
"Bi", yes I know it's a search word to bring up decent porn but in this instance it means that both the high and low beams are in the same unit. As standard, the Forfour has the dipped beam in the outside edge of the headlight unit and the high beam light sit on the inside edge of the headlight unit. With a Bi-xenon projector, it is moving both high and low beams into 1 unit.
The standard projector has a metal cut off plate between the bulb and the lens. This has the correct cut off line built into it. It is the same on the bi-xenon projector, the difference is that the cut off shield can move out of the way using a solenoid. With the cut off shield gone, the light output is unrestricted like a normal high beam light.
Here we see a standard Forfour headlight. Notice the lens is a bit frosty and has a line across it.
The frostiness increases light spread (fresnel effect) and the line makes the light cut off line better.
Pop off all the black metal spring clips located around the headlight. These fire off!
Heat the side of the headlight where the clear part joins the black part. This softens the sealant.
Eventually you should be able to lever the clear plastic lens away from the headlight unit.