I can vouch for the Lava Tube V4 got mine the other day really good they go from 3 - 6 Volts in 1 volt increments & they now tell you the Ohm's of your atomiser / cartomiser as well as telling you how much Volts the battery is at. I'm loving mine as well as my Ego C-Twist for out and about. that said my new little
Stealth Vape that I made (
it was my first mod build) is so small that might just become my out and about it runs at 3.7V and gives a nice vape only thing is i think it looks like a remote detonator so not to sure id take it near an airport (joke)
This is not the one I made but looks the same almost