DFBZ series fan is equipped with special fan motor of low noise and it is direct drive. The complete fan is made into square structure, good-looking appearance and reserve square hole on the wall and easy to install. The gravity type shutter is installed on the air outlet, in order to prevent back flow of outdoor rain and natural wind. It has obvious advantages of firm installation, small vibration, low noise, operating smoothly and steadily. So it is widely used in the wall-type exhaust air of mining and industrial enterprises, civil buildings, gymnastics, animal husbandry, entertainment venues and other places needing wall-type fan.