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. 6″ w x 6″ h outside flange dimensions. 4-3/4″ w x 5/8″ d x 4-3/4″ h return flange dimensions. Color finish is silver . Number of latches is 1 .