Abstract: A pressure stabilizing assembly for installation in an enclosure wall to prevent damage to the enclosure as a result of rapidly decreasing atmospheric pressure. The assembly includes a chamber with side, top, and bottom walls, a solid end wall, and an open face. The bottom wall has an opening therein, and a pivoted plate is provided for normally closing the opening, and allowing the passage of air therethrough only from the interior of the chamber to the exterior thereof, and then only under conditions of rapidly decreasing atmospheric pressure. A screen and bezel may be mounted on the portion of the chamber interiorly of the enclosure.