26" x 36" or 36" x 26" Cube Core Eggcrate Return Air Grille Compatible With Duct 8in actual front end outer dimensions

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

+ Product Details Size - 4"w X 34"h is the size for the duct opening measurement only

Ideal for Walls & Ceilings: Designed for seamless installation in standard 20" X 6" duct openings

Secure Locking Mechanism – Features a permanently attached eight-tumbler lock with a supplied key for added security

+ Product Details Size - 18"w X 24"h X 2"d (for duct opening measurement only)

26" x 36" or 36" x 26" Cube Core Eggcrate Return Air Grille Compatible With Duct 8in actual front end outer dimensions+ Product Details Size 26" x 36" or 36" x 26" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 27. 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