Tanks, also called clearomizers, are refillable reservoirs for the liquid or juice in a personal vapourizer that also contain the mechanism (atomizer) that produces the vapour. The atomizer inside the tank or clearomizer contains a coil and the coil contains some wicking material. The wicking material soaks up the liquid and the battery heats coil, which produces a vapour very much like steam when water is heated. There are many different tank brands and designs available and though they may look quite different, they work on the same principles. The coil/wicking part of the atomizer, called coils or coil head, does wear out and needs to be replaced periodically