These deodorant bars are totally natural and safe. Unlike the alum (aluminum) stone, they are not processed in any way except that they are carved from natural chunks of ancient Himalayan crystallized salt. They work when applied wet to clean skin - the deodorant stone leaves an invisible layer of protection that helps prevent odor-causing bacteria from forming. It leaves you feeling fresh and clean, but will not clog up your pores. Wash and dry area to be covered. Wet deodorant stone and wipe over the area thoroughly. Dry the stone and place it in a suitable receptacle. The stone may break if dropped onto a hard surface such as a washbasin, so stand away from vanity units when applying. These salt bars can also be used as soap for cleansing our bodies from bacteria. The deodorant/cleansing bar will last for months. Sizes and color may vary from picture.