DRY clean your shoes from the inside out! When your workout is finished, just place the ``Dogs`` in your shoes. Overnite they will absorb all sweat/water/moisture, leave a cedar aroma and kill all fungus/bacteria build-up. Red cotton flannel shells filled with crushed, treated red cedar dust. Now medically endorsed as an athletes foot fighter, they will also aide in the life of your shoes by preventing sweat corrossion.