I have three different Kayfuns.
1. ehpro Kayfun Lite+ in the black box. Comes with your standard keychain dual sided screwdriver, spare o rings, 510 drip tip adaptor and an additional full sized tank section if you chose to not use the metal ring sections. There is adjustable airflow via a screw at the bottom of the base and a fill hole on the other side of the 510 connection. polished stainless steel build. Mine was dirty with excessive machine oil when I purchased it at VaporCast here in Dayton, OH for $60. Also I don't see much difference in airflow when fully opened and think mine may have blockage due to a very loading whistle sound upon taking drags. The threads at the bottom of the base where the first ring is screwed down to are rather rough and crunchy. I love the materials used, not a fan of the whistle and some of its threads.
2. What I believe to be a Tobecco 3.1 clone from Fasttech. Might just be a Fasttech clone with no real manufacture name. like the 3.1, adjustable airflow and fill hole in the side of the unit and a collection deck. Also came just in a Baggie with o rings, pre made wick and coils, a clear tank section and has a mounted mouthpiece that screw in. Didn't come with a drip tip adaptor. Performs well and has great threading and machining. However, I'm not a fan of the fact its made of chrome plated brass. The plating on the outside of the unit started to wear off, I had to sand it off, leaving now a brass Kayfun...still plated in the interior. Also the fill hole port doesn't seem to work at all or barely. I always have to use the top fill method which causes leaks or floods 30% of the time.
3. hcigar 3.1. Nearly a 1:1 replica of the authentic Kayfun 3.1 and the Russian. Matt finished Stainless steal, same adjustable airflow as the Fasttech 3.1 and the authentic and has an insulated fill port making for much easier filling. Came in a zipper pouch with clear tank section the keychain screw driver, pre made wick and coil also came with the drip tip adaptor. Mouth piece screw in or so does the adaptor. The threads are buttery smooth and the machine quality is phenomenal. Mine came with a slight issue with one of the liquid channels...doesn't seem drilled out all the way to make connection with the base channel. Mine wasn't too dirty but caked galore with metal shavings and a few machine marked on the channel deck. Overall, its hard to tell the difference between this and the authentic that I compared with someone else's real deal. Performs just as good at a fraction of the cost.
If I had to rebuy any of these again, I'd happily rebuy the Hcigar clone and buy several of them to replace my two others. The ehpro one is decent but has some small issues that makes it an unpleasant vape(tired of sounding like I'm blowing a ref whistle) and the Fasttech one is chromed brass that will eventually wear off, and once the interior does the same....you may find yourself vaping toxic brass fumes. Two of my fav citrus flavors...ecto cooler from MBV and Queen of Sex from Starbuzz while leaking over a duration of a few months through the airport during the few leaking floods while filling it, the eliquid started to take the plating off around the hole. If it was doing that on the exterior, time would only tell when it happens internally. Unless you want to vape essentially Alzheimer's, be my guest.