This set does not include ballasts. You can use your own (for D2S bulbs) or you can use the ones that originally came with the car (Audi 4B0 941 471) which are readily available on eBay.
These HID projectors were used on various BMW, Audi and VW models and are a favorite for retrofitting other headlights. They are mounted with just a couple of mounting holes and can be easily adapted to various headlight configurations.
Unlike many other projector assemblies, these are very simple to connect. You have two wires for the ballast (12V) and another two wires (12V) to activate the solenoid which moves the shutter between high beam and low beam. So you have the same powerful bulb and lens for both high beam and low beams with instantaneous switching, all done in one assembly, no need for separate high and low beam lights. The lens is 2-5/8" in diameter, larger than most, which provides incredible illumation with a nice cutoff. You have to see it to believe it!
The bulbs are easily removable with a slight twist of the plastic retainer, easily accessible from the back. The Hella ballasts (if you choose to use them) are connected with a 14" high voltage cable to the bulbs which makes it easy to find a suitable location to mount these.
The bulbs and high/low beam solenoid are all fully tested and work fine. There is no rust or corrosion, they were stored in a dehumidified basement.