I have bought atleast 30 hid kits off ebay and online sources ranging from 35- 300 bucks, these are a nice set, These ballasts have a transformer that converts DC To AC voltage which is more stable and reliable then a DC only ballast. I have these installed in my 2010 Chevy Impala's fog factory projector housing. I had originally ordered the 8000K but Sonic was on a backorder, these 6000K are an acceptable replacment.