36" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Aluminum + Product Details Size – Compatible With Duct 7in Applications This sheet metal DDAG-A-1212

+ Product Details Size – 14" x 20" or 20" x 14" is the size for the duct opening measurement only

"Opposing" back blades

+ Product Details Perfect Fit & Easy Sizing - Designed for a 26" x 22" OR 22" x 26" duct opening (measured at the opening)

with an additional 1 7/8" width and 2" height

+ Product Details Size - 4"w X 22"h is the size for the duct opening measurement only

36" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Aluminum + Product Details Size – Compatible With Duct 7in Applications This sheet metal DDAG A 1212 + Product Details Size – 14" x 20" or 20" x 14" is the size for the duct opening measurement only "Opposing" back blades