6mg sits a step up from our lightest freebase strength, still made at 50/50 VG/PG and built for MTL pod kits rather than sub-ohm tanks. That balance gives a slightly stronger throat hit than 3mg, without losing the tighter, cigarette-like draw pod kits are designed around.
It suits light smokers easing off further, or vapers who found 3mg wasn't quite enough to feel satisfying. Works well across most pod kits, keeping things simple and low powered.