Originally Posted by calbert0 http:///forum/post/3189896
from what i understand......
Ballast' regulate the current so it is stable and constant because the metal halide bulb needs a steady and exact voltage to run.
This is correct. Ballasts also limit the current, and assist in igniting it by providing the voltage pulse necessary to strike the arc. If a ballast were not present, the lamp would destroy itself because the amount of current coming from a wall outlet is basically unlimited.
The short answer to the OP's seller is that if he has a MH light that is fully functional, then there is a ballast included in there someplace.