how often are you guys changing the cotton/wick you are using on these kayfun ?
I change mine about once a week. If you burn the coils you can keep the running for months. Also there are many kayfuns.... Kayfun Lite. Kayfun Lite+, Russian 91%, Russian, Kayfun 3.1, Kayfun 2.1. I have the Russian 91% and kayfun 3.1. Most people prefer the Kayfun Lite+ or the Russian 91% (basically the same exact thing, just slightly different.)
The Kayfun Lite does not have adjustable airflow. The Lite+ Has adjustable airflow but its on the base, whereas the Russian 91% has it on the side.
The Kayfun 3.1 is much like the Russian 91%, but it has an added well at the bottom for juice that drips down the air hole. This keeps your tank from leaking from the airflow valve. Also, it only has a tiny spot for you to fill with a 18 gauge blunt plastic tip bottle (can be quite a pain in the ....)
The Kayfun 2.1 is also known as the Kayfun Mini... Basically a smaller/thinner version of the kayfun lite+.
If you buy a clone a lot of people recommend EHPro.