Hart & Cooley 659 Series 20" x 16" White Return Air Filter Grille #043418 (Fits a 20"W x 16"H Hole) Designed to fit a 20"W x 16"H hole; actual size is 22-5/8"W x 18-5/8"H x 1-5/8"D. All-steel construction; bright white finish. 1/3" spaced fins set at 20 degrees. Use standard 1" thick disposable filters (not included). Removable face for easy installation and cleaning.