If the rings are CCFL (which are cold cathode tubes), then they will have somewhat of a ballast. The LED's just have a control board that contains the circuit and resistance to power them. The Umnitza kit includes 2 control boards - one for each side. One control board is encased in a small plastic box, and the other just has some thermal vinyl/shielding wrapped around it.
Maybe someone else can confirm, but I think the kit is based on what is in a BMW X5, which may be related to how the control boards are installed or mounted in that vehilce (as to why one is in a box, and the other is wrapped).