Depending on your safe's size, one of these should work fine. They have an indicator on them that let's you know when it's time to bake them out for re-use. http://www.cabelas.com/cabelas/en/templates/product/standard-item.jsp?_DARGS=/cabelas/en/common/catalog/item-link.jsp_A&_DAV=MainCatcat602007-cat601047-cat20799&id=0005567220673a&navCount=1&podId=0005567&parentId=cat20799&masterpathid=&navAction=push&catalogCode=XG&rid=&parentType=index&indexId=cat20799&hasJS=true
Desiccants