What is a good, reliable 600w attached ballast

I am wanting to upgrade from my 400w T5, Its been a good run I have ran her for 3 years now, But I want to fill my tent out. and yes 600 will do I don't want to go 1000. Local Store HTG supply has Digital Greenhouse complete sets bulbs hood, however they are not attached. I seen a attached ballast to lamp, however I cant remember where I seen it or who made it. Any experience and knowledge would be much appreciated. I am online researching my self also.

why would u want attached? I seen small lights likr that 250s I think