Louver Flange Kit, Material Aluminum, Rough Opening Height 18 in, Rough Opening Width 18 in, Overall Height 1 1/2 in, Compatible with Grainger Part Number 5NKH6, 5NKJ2, Includes Mounting Hardware, Overall Width 20 1/2 in, Overall Length 20 1/2 in. This item has been restricted from sale in the following state (s): []