Built-in copper core motor,high efficiency,low noise,smooth operation and long life 7 thickened fan blades,strong wind and more stable operation The exhaust fan is equipped with a check valve to effectively prevent foreign matter from entering the room and to prevent outdoor hot air and foreign matter from flowing back. Stainless steel material,smooth surface,high temperature resistance,long service life Strong suction,quick replacement of fresh air,suitable for a variety of scenarios