Fogger V4 is awesome, I've sold of most of my other RBAs and now have 2 of them.
I still have a Kayfun but doesn't get a look in these days.
The fogger is brilliant for the money and is my go to RBA now.
In regards to @
Jonshaw78 saying the fogger is a clone of the Kayfun / Taifun this isn't true although are similar.
The Kayfun is designed for single coils. It has a tight draw and is great for flavour but not so good for clouds but isn't really designed for that. It's also a pain if you have a full tank and need to tweak the build as you have to dump your juice.
The Taifun I do prefer to a Kayfun.
Slightly more airy drawer and more flavour than the Kayfun. Similar to build and the way it's designed (like a giant evod) you can flip it upside down, unscrew it and tweak the build without worrying about losing juice.
The fogger is a different animal.
The adjustable airflow means it's an airy draw fully opened up.
As a result it can blow great clouds and doesn't affect the flavour.
Not quite so noob friendly as it is designed for dual coils but it's still pretty simple, works well sub ohm (around 0.7 seems my sweet spot) and looks great on all my mods.
Considering the prices of a genuine Kayfun or Taifun vs the fogger and you can't really go wrong.