Constructed of a 24 gauge galvanized steel double panel door and frame with mill finish for long lasting durability. 1/8″ thick x 1/2″W closed cell neoprene gasketing between insulated door and frame assures tight seal without obstruction in air system. Frame includes 5/8″ notched knock over tabs. Door panel filled with 2″ fiberglass insulation compressed into 1″ and includes aluminum continuous piano hinge. 16″ W x 16″ H outside flange dimensions. 14-3/4″ W x 5/8″ D x 14-3/4″ H return flange dimensions. Color finish is Silver. Number of latches is 2.