Whether you're indoors or out, heat can slow you down — even make you sick. Now MiraCool® crystals can keep you cooler, more alert and productive all day long. Soak reusable bandannas and headbands in water for 10-20 minutes and they stay hydrated for days. Put them on and the power of evaporation works without ice to cool you down. Reusable. Choose from five good-looking designs.