The best I can find are Smok Shortys in 1.7ohm - but you'd need to punch your own hole - which maybe a PITA on that little thing.
I may just try it. I really like the size of the IBT halfling.
So, to address those about the different brass - of course brass can be made in varying amounts of copper and zinc - which will afford them different properties: weight, density, conductivity, appearance. I wouldn't say "quality' because that depends on the requirements of that specific alloy per manufacturers specs.
I know they have a coating on them. And certain that it makes them slightly magnetic. I stated earlier that I sanded one down and is now no longer magnetic. I believe they are using some sort of paramagnetic coating. Just not sure what. They won't say.
I've been vaping all day with my sweaty hands, outside, on my new Sigelei "Bagua" and it has not tarnished at all. You can see my finger prints and grease left on it, but that will just wipe off; no tarnish. It may after a few days, but I have not had it long enough.
My other brass devices (GV clones etc.) will start to tarnish within an hour.
Also, I mentioned before that I bought a 19E brass Extended (kick) tube - the i.d. is obviously a bit wide to accommodate the 19 inner tube. But I wanted to see how I could use it. I posted a pic in 8W modded 18350 mode. But I found a better use for it.
The "bagua" doesn't come with an 18500 tube - they don't make one. But this 19 brass Extended tube does - with a little space saving.
I screw the adjustable top pin in all the way and used an Efest 18490 flat top - fits very with no rattle

because it's so nice and snug. But I did notice that this tubes o.d. measures 23mm and the Bagua tubes measure 22.75mm - so it is very slightly wider and has that tiny overhang where it meets up with the button - unnoticeable at the top because of the ring. But it's nice to have the use of 18500.
Pic of it in this 18500 configuration next to its 18650 and 18350 tubes.
Oh, and that pic is with the 18350 tube that I've been using all day - no tarnish.