Measure Duct Opening for Proper Fit – Always measure the duct opening before ordering, as the listed size corresponds to the duct size. The outer frame is larger to ensure complete coverage and a clean, finished installation. Premium Aluminum Construction – Crafted from high-quality aluminum, this return air grille is lightweight yet strong, offering long-lasting durability for residential and commercial HVAC applications. Efficient Linear Bar Airflow Design – The linear bar pattern allows smooth, unobstructed airflow, supporting effective air return and improving overall HVAC system performance. Sleek, Modern Appearance – The streamlined linear design enhances ceilings, walls, or sills with a refined, contemporary look that blends effortlessly with various interior styles. Versatile & Easy Installation – Designed for use on ceilings, walls, and sills, this return air grille installs easily and fits securely for dependable, maintenance-friendly performance. 8" X 4" Linear Designer Aluminum Supply Air Grille – for Ceiling, Wall, Floor Use - HVAC Vent Duct Cover Diffuser – [White]