Anything you wish.  Mine is a 7" bottom mount I got on eBay for $40 delivered:

The head light uses a common auto bulb (H4 I think). There are many different flavors for these that are vailable. There are some threads in the forum covering this in detail

about anyting you want. I put this on mine. I didnt pay that much for it tho. got it off Ebay WAY cheaper.

http://www.russwernimont.com/store/product_info.php?cPath=3&products_id=62

I didn't ride at night at first because the light didn't light up much.  Then I realized that it was aimed down too far.  The low beam was at about 50 feet out.    At 45 mph 50 feet is nothing.

So...... I adjusted the alignment to match my auto.  Two screws pivot the bulb in the housing in a trianlgular fashion.  It's a world of difference.

lol.  I also run my high beam pretty much whenever I ride my bike.  I got that tip from my instructor at the Basic Motorcycle Riders Safety Course.  Its like he said, how are they going to know unless they pull up beside you and see the little blue light on?  Besides, it definately makes you more visable.

il67bp wrote on 11/10/08 at 23:58:17:

Becarefull with a true HID conversion, may be illegal in your state.
Some state that in order to use it, it has to be a factory install.
Some HD's have it, if you can find one and want to do it, that's the way I'd do it.

If you read the ads for HID conversion kits, most say not for street use in one way or another.  If you're in a state where there are inspections, you'd have to reinstall the stock lamp for inspection.  Cheap HID's are low beam only, but aren't shielded not to cast light in the high beam.

IMHO, it's not the type of light (halogen vs HID) it's the lense.  I have a stock 55/60 bulb.  In highbeam the light is ample, but low beam is as good as moon light.  Someday I'll gather up some lenses and find out.