18" x 36" or 36" x 18" Cube Core Eggcrate Return Air Grille w26h26 Ideal for Walls & Ceilings:

Ideal for Walls & Ceilings: Designed for seamless installation in standard 16" X 6" duct openings

+ Product Details Size - 26"w X 16"h is the size for the duct opening measurement only

12" Diameter Is The Size For The Duct Opening Measurement Only

simply pop the diffuser into the wall duct hole and let the side springs hold it securely in place

14" Circular Round Aluminum HVAC Supply Grille Air Diffuser - With Butterfly Damper - Vent Duct Cover

18" x 36" or 36" x 18" Cube Core Eggcrate Return Air Grille w26h26 Ideal for Walls & Ceilings:+ Product Details Size 18" x 36" or 36" x 18" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 19. 75" X 37. 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