FireEx protects your home from chimney fires by smothering chimney fires safely and quickly. FireEx was designed with safety in mind and can be used with ease in a time of need by simply tossing the entire packet into the fire. Once the product meets a burning fire, the chemical reaction will result in the formation of a zinc oxide cloud to suffocate the flames. Try to eliminate any drafts by either closing doors or covering opening with fire retardant material. Larger stoves or fireplaces may require two packets. FireEx is an excellent fire safety item to stock up on as its airtight plastic packaging ensures an indefinite shelf life.