Naiture 4" x 10" Solid Brass Wall Register Mission Style Chrome Finish Duct opening size: 4" x 10" (5-1/8" x 11-1/4" Overall) Made of heavy-duty solid cast brass for durability. Finished with a durable chrome powder coat finish to resist rust. Louver control extends 3/8" H from vent which could control air flow easily by foot. Includes four tension springs for securing into wall ducts. No screws required. To determine size needed, measure air duct opening rather than old register or grille.