Firestop intumescent door seals are designed to close the gap between the fire door & frame in the event of a fire thereby preventing the spread of smoke & hot gasses. Once installed our seals can lay dormant for many years only activating when exposed to the rising temperatures & pressures in a fire situation. Firestop’s high performance intumescent core contains intercalated graphite which in the event of a fire expands multi-directionally up to 10-15 times its original size sealing the gap & holding the fire door in place. Certifire approved & Fire door rated. Comes with a 10 ye...