National Guard Products' Finger Guard is designed to help prevent injury to fingers accidentally placed in the hinge area of a door. This unique product features an internal spring mechanism that maintains constant tension against the polyethylene fabric which helps prevent fingers from entering the dangerous area behind the edge of the door. Durable "endless cycle" spring mechanism. Order 2" less than opening height to allow for the stop on the door frame head and door bottom undercut, not field sizable. Fire rated up to 3 hours metal doors, 1 hour wood doors.