WELLAND 4 X 12 Inch Red Oak Wood Vent Self Rimming Floor Register Vent Cover Grille Unfinished with Damper Fits a duct size opening of 4" x 12", Overall dimension is 13.6" x 5.6" x 0.75" Made of Unfinished Solid Grade A Red Oak Wood Self-rimming (drop-in) installation, louvered design Also known as insert vent, comes with metal damper installed Metal damper allows airflow to be switched on and off