An astragal is a piece of hardware that is used on a pair of doors to seal the gap between the doors when they are closed. An "Overlapping Astragal" is attached to one of the doors in a pair of doors and when the door is closed the astragal will overlap the edge of the other door. "Meeting Stile Astragals" meet in the middle when the doors are closed to seal the gap between the doors. If you have a space between a pair of doors, use an astragal to close the gap. You can also be used to cover the space between the top of a door and a flush transom panel where there is no mullion, or between the top and bottom leaves of a Dutch door.