In a fire, airflow is the enemy. It feeds the flames and speeds up the spread of harmful gasses and toxic smoke. GREAT STUFF™ Fireblock seals the spaces around your pipes, cables and ducts and inhibits the spread of air (and gasses and smoke) from one story to the next. And that could give you and your family precious time to respond and evacuate. The fact that it also helps to conserve energy, reduce drafts and save on heating and cooling costs is just a bonus.