Subtanks are generally used on mods which produce more wattage or voltage to the atomizer. Sub Ohm Tanks are a popular option for vape mod users who want big clouds without the hassle of dripping eliquid onto their Rebuildable Drip Atomizers (RDA). Get the cloud output equal of an RDA and the convenience of a refillable tank. Sub Tanks have evolved into robust reliable atomizers built specifically for large capacity vape mods. Replaceable coils are generally split into OHM loads and should be matched appropriately with the output wattage of your vape device. (TC) Temperature control is another popular feature when using subtanks giving the users the ability (if using a TC specific coil) to control their vape at a certain temperature making sure that temperature is never exceeded leading to slightly better flavor with a little bit of lost vapor.