When I put my Mini Novas on my twists, I use the little couplers/spacers (thread sleeves) to fill that gap between the threads and the tank. In my case, I got the little thread sleeves from GotVapes, type "B" (I ordered black, they sent me chrome, I don't think it matters as far as construction). If the tank is screwed on all the way, and the thread sleeve is all the way down, there is still a gap (not huge, but noticeable) between the bottom of the tank and the top of the thread sleeve. I can loosen the thread sleeve from the battery and move it up closer to the tank. By doing this, I can effectively control how airy my draw is. If I screw the thread sleeve up flush against the tank, the draw is very tight. I can't imagine it's supposed to be this way, but it's a fairly useful "flaw".