16" x 18" or 18" x 16" Cube Core Eggcrate Return Air Grille Color_Red Oak and extends HVAC system life

and extends HVAC system life

Actual Filter Size – 31 3/4"w x 19 3/4" x 1"

Ideal for Walls & Ceilings: Designed for seamless installation in standard 10" X 8" duct openings

actual front end outer dimensions are approximately 20 5/8" width X 26 5/8" height

Actual Filter Size – 19 3/4"w x 15 3/4" x 1"

16" x 18" or 18" x 16" Cube Core Eggcrate Return Air Grille Color_Red Oak and extends HVAC system life+ Product Details Size 16" x 18" or 18" x 16" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 17. 75" X 19. 75". High Quality High quality, rust free aluminum construction with smooth finished edges and counter sunk screw holes (screws included); no sharp edges.. Installation Location sidewall and ceiling. Design Cubic core eggcrate design Offers highest airflow efficiency at almost 95%, reducing