Bottom filled electronic cigarettes

 

— as the name implies, the liquid in this case is poured into the tank from the bottom side; for this, the atomizer inevitably has to be turned over. This is somewhat less convenient than top filling. At the same time, this design allows you to change the heaters (or remove them for rewinding) without draining the liquid from the tank. Note that "squonk" formally also refers to the bottom filling, however, this method has its own specifics, which is why it is taken out separately (see the relevant paragraph).