Hart & Cooley® Return Air Grille, Series: RH45, 24 x 12 in Size, 23-1/2 in Duct Width, 11-1/2 in Duct Height, 13-3/4 in Overall Width, 1 in Overall Depth, Fixed Blade Grate, 520 to 1300 cfm Flow Rate, 1.29 sq-ft Effective Area, 45 deg Deflection Angle, 3/4 in Blade Spacing, Aluminum, White Painted, Domestic