Here's a diagram for the super-slim e cig. It's a very simple device which is basically a narrow, hollow straw containing just a heating coil and ss mesh to suspend the juice.
The lightness in weight
the small size and dexterity
the easy 'open' air draw-through
the 'depth' the ss mesh gives to the vapour quality and
the closeness of the coil to the open mouth end (it pretty much sits between vaper's lips)-
- all come together to make this device feel incredibly close to smoking a real cigarette.
Of course, the tube sometimes 'flash-heats' (if the juice is running low), but a simple un-powered suck to draw in fresh air instantly cools it off again. The open draw, as well as producing the vapour, also acts to effectively regulate the heat of the device.
As there is next to nothing else in the tube, it does not matter if too much juice is dripped in... a short blow into the mouth end quickly disperses any excess. Similarly, if a draw is sounding 'bubbly', a quick, gentle blow instantly optimises the juice primed in the mesh.
Two drops of juice equals about the same as an analogue cigarette (although I've been topping this up with five or six drops). With no end caps to prise off or fiddly threads to unscrew, the actual process of picking up the bottle and depositing a few drops into the open mouth end - before inhaling a fresh and instantly intense mouthful of vapour - now feels like a pleasurable part of the vaping experience.
There have been a few times over the last four days when this little e cig has been out of action (due to modifications) and I've had to go back to my regular kit... I sorely missed it!
