The square diffuser has straight and straight lines, the blade inclination angle is 37°, and the airflow is attached (flat). The whole blade and the frame are separated. The whole blade can be easily taken out in the frame for easy installation and cleaning. Different sizes of diffusers can be selected according to the spatial characteristics, and can also be used with the herringbone gate. Suitable for studios, hospitals, theaters, classrooms, concert halls, libraries, amusement halls, theater lounges, general offices, shops, hotels, restaurants and stadiums.