Use these desiccant packs to knock down humidity in home and office safes. * This item contains qnt (12) desiccant packs. The 12 desiccant packs are sealed in plastic bags for shipment. * This item is appropriate for up to a 7 cubic foot sized safe. A rule of thumb for storage is to use 1 Unit of desiccant for each 0.6 cubic feet (90 cubic inches) of enclosed space. * These Tyvek enclosed desiccants are Food/Pharmaceutical grade so you can be confident they won"t damage the contents of your safe. * After use they may be reactivated by heating in an oven. Reactivate bags by heating to 245 degF for 16 hours. Note that the Tyvek package melts sharply at 275 degF. A residential oven may overheat the and melt the packages even if set to 245 degF; so be careful.