I have the 18" golden rod, tried the gel packs you have to dry out every so often. Had to set reminders to do that. the golden rod you plug in and just check to make sure it is still working when you pull a gun from the safe. The check is that rush of warm air when you open the door.
these are places I have found with the best prices in no order.
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http://www.westmarine.com/buy/golden...12_360_002_501
http://www.deansafe.com/golden-rod-3...ifier-rod.html
http://www.btibrands.com/product/dehumidifier-rod-18/
http://www.brownells.com/gunsmith-to...-prod1703.aspx
Al