RDA (Rebuildable Dripping Atomizer) – has no tank section to hold e-liquid. They’re designed for e-liquid to be dripped from a bottle, drop by drop, directly onto the coils and/or wicks (usually after removing the cap, which is then replaced after dripping). Sometimes the decks have a well under the coils that holds a small amount of e-liquid, usually less than 1ml. A commonly held opinion in the vaping community is that RDA’s produce purer and more intense flavor than any other method of vaporizing. Thus, RDA’s represent the gold standard against which all other types of atomizers are measured.