Just as a word to the warning, for you and everyone who for some reason continues to cling to these - We’re over three years from them discontinuing the keyfobs. While there certainly has been no official word? I would honestly be phasing over to the mobile authenticators sooner rather than later.
What if tomorrow Blizzard decided they would no longer be compatible or valid and that the mobile authenticators would be the only way to go and cut off the old fobs entirely? The batteries only last so long (though some people have still cracked them open and replaced them somehow). They are outdated and there is nothing to guarantee how long they’ll be supported.
Just some food for thought.