20" x 36" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Insulated Line actual front end outer dimensions 4 X 12 Is CRFG2028 Width_14in

actual front end outer dimensions are approximately 30 5/8" width X 10 5/8" height

+ Product Details Perfect Fit & Easy Sizing - Designed for a 12" x 8" or 8" x 12" duct opening (measured at the opening)

+ Product Details Perfect Fit & Easy Sizing - Designed for a 8" x 18" or 18" x 8" duct opening (measured at the opening)

Actual Filter Size – 17 3/4"w x 31 3/4" x 1"

+ Product Details Size – 20"w X 50"h is the size for the duct opening measurement only

20" x 36" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Insulated Line actual front end outer dimensions 4 X 12 Is CRFG2028 Width_14in actual front end outer dimensions are approximately 30 5 8" width X 10 5 8" height + Product Details Perfect Fit & Easy Sizing Designed for a 12" x 8" or 8" x 12" duct opening (measured at the opening)