You will need a fixture and a cord.

I don't know what kind of ballast you are talking about, so I will assume the usual 'horticultural ballast' sold by grow shops. You will need a fixture and a cordset. The cordset has a HID socket and a cord with the special end that will fit into the output of your ballast. If you want to do the vertical bulb thing where the bulb protrudes down trhough a hole in the top of your grow area, you're good with ballast,bulb,cordset.

Hope that helps, I really reccomend you talk to someone at a shop about this. It's not always obvious from the product descriptions that you need cordset, fixture, etc.
FatSean Reviewed by FatSean on . If I buy a ballast and bulb, I'm good right? As in, I don't need to buy another lighting fixture? I'm just doing a small grow box where the light will sit at the top of the tub, will the ballast actually have the component where the bulb will screw into it or do I have to buy some sort of lighting fixture separately? Thanks. Rating: 5