Air diffuser and air grille are usually made of extruded aluminum with powder coated, they are mainly used for ventilation and air conditioning system for air supply, air return, can be directly installed on the end of the pipe, the ceiling, the wall or the door. They are many types: square ceiling air diffuser, ball jet diffuser, slot diffuser, swirl diffuser, return air grille, supply air grille, linear air grille, door grille and other grilles.