Naiture 4" x 10" Solid Brass Wall Register Traditional Style Chrome Finish Duct opening size: 4" x 10" (5-5/8" x 11-1/2" Overall) Made of heavy-duty solid cast brass for durability. Finished with a durable chrome powder coat finish to resist rust. Removable louvers. Louver control extension from register: 3/4" which could control air flow easily by foot. Includes 2" matching screws and all the necessary mounting hardware. To determine size needed, measure air duct opening rather than old register or grille.