Double doors require specialized hardware to prevent forced entry. Specify Multi-point Locking Systems that secure the door at the top, middle, and bottom. For the inactive leaf (the door that stays closed), ensure it is equipped with heavy-duty flush bolts. Hardware should be rated Grade 1 or Grade 2 by ANSI/BHMA for durability. If sourcing for smart buildings, confirm compatibility with electronic strikes or smart locks and ensure the door prep (bore holes) matches international standard backsets (usually 2-3/8" or 2-3/4").