18" x 20" or 20" x 18" Cube Core Eggcrate Return Air Grille Color_Red Oak Wood Actual Filter Size – 15

Actual Filter Size – 15 3/4"w x 33 3/4" x 1"

actual front end outer dimensions are approximately 26 5/8" width X 12 5/8" height

+ Product Details Perfect Fit & Easy Sizing - Designed for a 26" x 32" OR 32" x 26" duct opening (measured at the opening)

Actual Filter Size – 15 3/4"w x 17 3/4" x 1"

Actual Filter Size – 29 3/4"w x 33 3/4" x 1"

18" x 20" or 20" x 18" Cube Core Eggcrate Return Air Grille Color_Red Oak Wood Actual Filter Size – 15+ Product Details Size 18" x 20" or 20" x 18" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 19. 75" X 21. 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