The Lot of 2 -4x4 Inch Duct Opening Linear Aluminum Clip-On Bar Return Air Grille by Hvac Premium is a set of two silver aluminum bars designed to be clipped onto 4x4 inch duct openings. These bar return air grilles are lightweight at 0.4 pounds and come in standard packaging. The linear design of the bars allows for easy installation and efficient airflow in heating, cooling, and ventilation systems. Perfect for home improvement projects involving HVAC systems, these grille inserts provide a sleek and functional solution for maintaining proper air circulation.