A flange is not needed, although the sudden absence of one may allow you to do one of the silly things all carto users had done, like try and remove your drip tip when your tank is not installed on your mod, and end up with a spill. You can still use flanged cartos if you want to.
The Phiniacs is going to hold your carto MUCH tighter than your current tank, so those kinds of accidents won't be as easy.
As for which carto brand, everyone has their favorites. I prefer Ikenvapes but they are often out of stock. I use Boges as backups.
I also prefer darker juices so I choose cartos with larger holes, or slotted. Both Boge and Ikenvape offer those. That may give you longer service than the Smoktechs.
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