Naiture 6" X 14" Cast Iron Wall Register Victorian Style Duct opening size: 6" x 14" (7-5/8" x 15-1/2" Overall) Made of 8mm-thick 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. 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.