Our 24 gauge galvanized steel Duct Access Doors are 1” (25) thick, insulated, and of double wall construction. To ensure a tight seal without obstruction in the air system, gaskets are installed between the door panel and frame. The frame has knock-over tabs and easily attaches to the duct. A piano type hinge ensures easy operation. The door is secured with a self-tightening cam latch that is hand operated.