Lockdown Silica Desiccant Dehumidifiers provide a lifetime of protection for firearms, drawers, safes, cabinets, vaults and closets. Prevents condensation, rust, mildew and corrosion. The silica gel creates a protective shield of dry air within enclosed areas. The crystals change color once they are fully saturated, and can easily be recharged in an oven. Non-toxic and safe to use. Features40 gram (protects 3 cubic feet) or 750 gram (protects 57 cubic feet) sizes for various needs RechargeableGreat for gun safes and other storage areas