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