The Stack-On SPAD-100 Rechargeable Cordless Dehumidifier is perfect for use in safes and security cabinets. It absorbs excess moisture without having to drill holes or run electrical cords through your safe and doesn't even require batteries. It features a moisture gauge on the front of the dehumidifier that indicates when it needs to be recharged. It can pull excess moisture from up to 100 cubic feet for 4 to 6 weeks before it needs to be recharged. Recharging is simple, just plug it into a standard electrical outlet overnight and the SPAD-100 is ready to go.