A little something about the design of the GS2 I noticed and don't particularly like is the o-ring that seals the bottom of the tank seems to be doing double duty. It keeps the upper AC ring firm as well as seals the tanks bottom end, it really should have two o-rings in that area (IMO). I have only clones so I can't compare to the original but figure it's the same. On my 19 mm Hotcig GS2 the bottom of the tank never even touched the o-ring. I fixed that though. Also I'm not to sure how much it matters as there are plenty of fine threads that probably make the seal well enough.