Pairs of doors that do require an astragal shall have at least one that projects a minimum of 3/4-inch beyond the edge of the door to which the astragal is attached. Pairs of doors that are in a required means of egress may not be equipped with an astragal that inhibits the free use of either leaf. An astragal may not be used on pairs of doors with vertical rod exit devices on both leaves of the pair. Pairs of three hour doors always require an astragal per NFPA 80. Other combinations of fire exit hardware on the active leaf and a vertical rod device on the inactive leaf are acceptable. In some situations a coordinator may be needed to allow the inactive leaf to close ahead of the active leaf. This ensures proper latching of pairs of doors. Some manufacturers are able to supply labeled pairs of doors with an open-back strike without an astragal, which eliminates the need for a coordinator.