The ones you saw are probably not HID, even though they may say they are HID. They are just regular halogen bulbs with blue colored glass, in other words, worthless. HID kits include the bulbs, 2 ballasts/ignitors, wiring harness and/or relay. They may or may not include what is in the pic below. The color temp of the bulbs is based on the Kelvin scale. Please note that the higher the number doesn't mean the brighter it gets, actually quite the opposite. The higher on the Kelvin scale the bluer/purple the light is and the less light output you will have. The lower Kelvin the more yellow the light will get. For maximum light output/whiteness I suggest getting 4300K or 5000K bulbs. Pros: more usable light on the road, easy install. Cons: your headlight housing is uses reflectors to shine light on the road. Putting an HID kit in there will produce glare for oncoming drivers. A full retro fit with projectors is recommended. For more HID info I would suggest heading to hidplanet.com.