a romanian blog finding on this here.
i’ve searched for places to buy a cannister of each in bucharest. wouldn’t spend more than a few minutes on it, but nonetheless i found a site that brokers helium, and not a single one for commercial use of SF6. it seems to have something to do with conductors, or general electricity.
update: xenon seems to accomplish the same thing as SF6. for more money. dunno about availabilty