Duct opening size - 3 (height) x 9.5 (width) BG38 Herringbone return (no damper) with no screw holes and with beveled edges and a minimal flange along one long side
Duct opening size - 4 (height) x 10 (width) BG38 Herringbone supply (with damper) with no screw holes and with beveled edges
