Agricultural Wall Exhaust Shutter / PVC Shutter Fits Fan Dia 16 In. Overall Square 19 In. Opening Required 16-3/4 in x 16-3/4 In. Frame Depth 1-1/2 In. Open Depth 3-1/4 In. Flange Width 1-1/2 In. Free Area 1.406 sq.ft. Max Velocity 1500 FPM Vertical Mounting Position Blade Material Black PVC Extruded Aluminum Frame with Yellow Zinc Dichromate Rods For Use With Poultry and Swine Confinement Operations and Anywhere Corrosion is a Problem Number of Panels 1