The full form of RDA stands for (Rebuildable Dripping Atomizer). In this the vaper is needed to manually put few drops of E-Juice on top of the coils and wicks. In this the juice section is at the bottom of the build deck for storing the Vape Juice and later on end points of the wick is dipped into the vape juice tank. The general size of the Vape Juice Tank is not bigger. This requires manually re-filling of the E-Liquid and this way wicks are always dipped in to the liquid and prevented for becoming dry.