16" x 18" or 18" x 16" Cube Core Eggcrate Return Air Grille Compatible With Duct 8in this guard fits almost any

this guard fits almost any thermostat and blends seamlessly into any setting

Actual Filter Size – 11 3/4"w x 5 3/4" x 1"

Actual Filter Size – 17 3/4"w x 5 3/4" x 1"

and Diffusers

16" x 18" or 18" x 16" Cube Core Eggcrate Return Air Grille Compatible With Duct 8in this guard fits almost any+ Product Details Size 16" x 18" or 18" x 16" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 17. 75" X 19. 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