Hart & Cooley by Duravent, 672 20 20 W, Air Grille, Series: 672, 20 in W x 20 in H Size, 19-1/2 in Duct Width, 19-29/32 in Duct Height, 21-3/4 in Overall Length, 21-3/4 in Overall Width, 5/16 in Overall Depth, 540 to 1081 cfm Flow Rate, 269 sq-in Effective Area, 40 deg Deflection Angle, 1/2 in Blade Spacing, Steel, Bright White Enamel, Domestic,