Naiture 2-1/4" x 10" Flush Mount Wood Floor Register, Vent Cover Grille, Unfinished Red Oak Duct opening size: 2-1/4" x 10" (4-1/2" x 12" Overall) Made of high-quality 3/4"-thick unfinished red oak wood To install flush with hardwood flooring, the overall measurement must be cut out. This wood floor grille mounts flush with your hardwood floor, and can be stained to match. To determine size needed, measure air duct opening rather than old register or grille.