Naiture 4" x 10" Side Wall Register, Return Vent Cover Grille, Unfinished Maple Duct opening size: 4" x 10" (5-1/2" x 11-1/2" Overall) Made of high-quality 1/2" thick unfinished maple wood. Includes mounting holes but no mounting hardwares. Crafted from durable wood, this wall return is easy to install and built to last. To complement the style of your room, leave this product as is or add a finish to match your decor. To determine size needed, measure air duct opening rather than old register or grille.