For a duct size of 14" x 18", Adding louvers is an easy way to control air flow and increase cooling and efficiency. Our high quality louvered assemblies fit behind the Scroll and Square Grid Pattern grilles and can be adjusted easily with a key to tune the volume of air moving through your unit. Louver units include foam strips for proper installation and a tuning key. (In some instances you may need to remove the grille to adjust the louvers). These louvers are a great way to add extra versatility and control to your heating and cooling system.