I just recently started using tanks instead of cartomizers alone and it amazes me the money I am saving on juice. With my XXXXL cartomizer, it would suck up the juice and I would still get a dry vape unless I pushed 4 volts through it. With my Kanger, the juice seems to last forever and you use every drop. Same thing to a lesser extent with the Boge F16. The tank manufacturers should capitalize on that in their advertising.