Intumescent Strip Fire and Smoke Seal 2.1m White are designed for using with a fire door. It is an intumescent graphite based fire seal contained within a PVC sleeve for fitting into a rebate to either the leaves or the frame of a door. In the event of a fire the seal expands to many times its original volume to close the gap around the door and prevent the passage of fire, smoke and hot gases. It provides a safe and effective barrier.