A "Golden Rod" is the best first defense item I've found. In addition, I keep a wool sock full of regenerative silica beads in there. I watch the humidity on a guage inside the safe and it doesn't fluctuate much with or without the beads, so I figure the "Golden Rod" is doing the most work. Chances are, if your safe is ground floor/inside, and you don't live on the coast, then humidity shouldn't be a problem for you. But, if it's in your basement or you do live on the coast, then you most likely need something to deal with moisture inside the safe. My .02
