Just saw where Pbusardo did a review of the Siam tank. In the comments the guy who make's them said he'd start offering tighter o-rings. Pretty good cs imo.
Once they make them tighter I'll have to get a couple combinations. They do go really well in the Provari's.
I think there may be another minor design flaw with those tanks: the caps don't go far enough into the tank to really hold well. I think they need to redesign them to be deeper, for a better grip. The J-Tank gets this part right, so that the tank takes considerable effort to take apart, which is a good thing when pocketing Provari plus tank.