If you use the Kayfun more, it becomes second nature. The Kayfun is what I use most of the time and I never forget to to open the JFC.
I have a difficult time keeping tracking who did what first but there's a similar top load design for the Dvarw from Steam Turners.
I haven't tried the one for the Dvarw or the Doggy yet but it does seem makeshift compared to the elegant design of the Kayfun Prime. In the video of the authentic Doggy 2k18, it looked like some liquid squeezed out when the top cap was pushed in while the tank was held upside down. Although it looks jury rigged, I would like to try it.
I think the simplicity of the Doggy is the best thing about it. It is easy to break down and clean. And that's the primary reason that I got into rebuildables. Some have posted that they don't clean their tanks for months so it may not be important for them but I like to clean frequently.
I do prefer the vape from the Kayfun for my low air flow style of vaping (I think maybe the narrower and longer chimney and the better air flow control might be the reason for this preference). But it is convenient that I can break down and clean the Doggy in a fraction of the time. The air flow ring on the Doggy does irritate me though. The Prime has a lot more parts so I keep several in rotation. I can just grab a new one and clean the old one when I have time.
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