30" x 26" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Compatible With Duct 10in + Product Details Perfect Fit 4 X 12 Is CRFG2028 Width_14in

+ Product Details Perfect Fit & Easy Sizing - Designed for a 18" x 22" OR 22" x 18" duct opening (measured at the opening)

Ideal for Walls & Ceilings: Designed for seamless installation in standard 24" X 6" duct openings

actual front end outer dimensions are approximately 24 5/8" width X 20 5/8" height

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

+ Product Details Size – 12" x 12" is the size for the duct opening measurement only

30" x 26" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Compatible With Duct 10in + Product Details Perfect Fit 4 X 12 Is CRFG2028 Width_14in + Product Details Perfect Fit & Easy Sizing Designed for a 18" x 22" OR 22" x 18" duct opening (measured at the opening) Ideal for Walls & Ceilings: Designed for seamless installation in standard 24" X 6" duct openings