Abstract: An assembly for sealing a fire resistant door within a door frame during a fire event is provided. The fire resistant door has a plurality of edges. The assembly comprises a first body portion and a second body portion secured to the first body portion. An expansion mechanism between the first body portion and the second body portion for moving the second body portion in a direction generally away from the first body portion and against the door frame upon attaining a predetermined temperature with the first body portion, the second body portion, and the expansion means forming a door edge device wherein the door edge device is secured to at least one of the edges of the fire resistant door.