Naiture 2-1/4" X 12" Steel Louvered Floor Register with Damper or Lever Contemporary Style, Oil Rubbed Bronze Finish Duct opening size:2-1/4" X 12" (Overall size: 3-1/2" X13-1/4") Made of heavy-duty, 2 mm thick steel against rust. Finished with a durable oil rubbed bronze powder coat finish. Louver control extension from register: 5/8" could control air flow easily by foot. To determine size needed, measure air duct opening rather than old register or grille.