... 2. used in return air and exhaust application 3. good quality Detailed Product Descriptionsquare aluminium diffuser, air diffuser, aluminum diffuser, air grille,ventilation, HVAC 1 ... closing. 2.Material Extrude Product Name:square aluminium diffuser, air diffuser, aluminum diffuser, air grille,ventilation, HVACMaterial: AluminumCorlor:white powder coatedSize:Different sizes ...