Light/Ballast Question

so im sure this is gonna be a newb question so i figured id ask, im looking to order my lighting system in next couple days already know whcich system im ordering but befor i do i had a question

i understand you have the ballast,reflector,light ect, but if you were to order these pieces seperately which item does the socket comes with ? the reflector ? the ballast ? again im a newb so figured id ask , ive seen a few items like http://www.customaquatic.com/estore/control/product/~product=LT-SG250310 that have it with the reflector then i see a http://www.plantlightinghydroponics.com/600w-hps-ss10-remote-ballast-p-1385.html that has a detachable one thats option with it so i figured id ask

The socket comes with the reflector, you can see it in the picture.

I see you are shopping online. Think about buying from a local vendor. at least talk to them. If you ballast fails, your local shop may give you a loaner while the broken one is fixed. They do it at my local shop.

If you need to deal with an online vendor and your ballast breaks, it may take a couple of weeks and the are very heavy and cost a lot to ship.

Just my $ 0.02