Naiture 9" x 12" Oversized Cast Iron Wall Register Antique Style Duct opening size: 9" x 12" (11" x 14" Overall) Heavy cast-Iron with rustproof black powder coat finish for durability and reliability. Louver Control Extension from Register: 3/8" which could control air flow easily by foot. Register will have mounting holes drilled before shipping and includes two 2" screws in a matching finish. Included all the necessary mounting hardware. To determine size needed, measure air duct opening rather than old register or grille.