I've had one of these for over 10 years now and purchased this one as a spare in case the original ever breaks.These work extremely well. The only downside is that they are powered by 120V A/C so you have to run a wire inside your safe. Some safes have a power strip already inside, some have punch-out holes to run cords, and some have no holes. You should figure out what your safe has before you order.You have to buy the right length rod to match the interior air volume of your safe. Make sure you buy a small hygrometer and thermometer to keep in your safe as well so you know what your humidity and temperature levels are.DRI-ROD sizing guide:8" = 50 cu.ft12" = 100 cu.ft18" = 200 cu.ft24" = 275 cu.ft36" = 275+ cu.ftAccording to the NRA National Firearms Museum:50% humidity at 70 degrees is considered ideal "Arms Museum" storage conditions.-----------------------------------------------------------------------------------------------From the Manufacturer's Website:Dri-Rod Function: The rod works off a rather simple principle. The rod will heats up to a surface temperature of 125°F and circulates warm air throughout the enclosure. The warm air rises, while the cool air drops.With this constant air circulation process it eliminates musty smells and dampness and the content in the safe, closet or other enclosure will be protected from rust, mildew etc., as well as dries out any moist air within the safe.Dri-Rod Installation: The Dri-Rod Dehumidifying Rod should be installed in a low horizontal position, mounted to the side wall 6-8 inches from the floor.Electricity Consumption: Most of our units only draw 7 watts or 10 watts.Dri-Rod Safety: The Dri-Rod dehumidifier is unique in that it is made of unbreakable materials. No glass tubes are used, in our manufacturing process.