Have a look here.
Mech Mods - modsandatties.com
How can I put it? It's another world beyond the normal world of e-cigs.
They are ALL tubes that take external batteries. You either have to take whatever power is on offer from the battery (4.1 volts, dropping to lower) or use a special additional module (a kick) to set the power.
I have 3. They are great. Takes a lot of experimentation.