I'm sure they realize how heavy your box is. They may see you open it. So, they know you have precious metals in there. Sure, they can't open it without your key and theirs. But, does it bother you that they know? Does it bother you your gold and silver sits in that box away from you for months or years at a time? Do you check it weekly? Do you add your own lock? What do you do for extra assurance? Do you NOT use a box?