Naiture 4" x 10" Roundover Wood Floor Register, Vent Cover Grille, Wood Louvered or Drop-in Style, Unfinished Cherry Duct opening size: 4" x 10"(5-3/4" x 11-5/8" Overall) Made of high-quality 3/4"-thick unfinished cherry wood Designed for hardwood floor installation. The smooth, round edges of this grille make it a popular item. Single piece, come with no frame. To determine size needed, measure air duct opening rather than old register or grille.