RBA bases & adapters
Some clearomizers can only use premade coils, while some may use an RBA base that replaces the coil. In the RBA base you install an RBA coil, in which you thread cotton through, just as you would in a RBA tank. With a coil you wrap yourself you'll save a buck in comparison to premade coils, and you'll get stronger flavors and thicker vapor. Here is also adapters making coils fit tanks they dont fit by default.