The exhaust fan is

mainly installed on the wall or window for ventilation and exhaust.
1. One-way exhaust fan: When the exhaust fan is turned on, the dirty air or smoke in the room can be discharged to the outside. When it is not turned on, the shutters will automatically close, which can cut off external pollution.
2. Two-way exhaust fan: It can exhaust the dirty air in the room outside, and can also suck the fresh outdoor air into the room to achieve the purpose of two-way ventilation.
3. There are three shapes: square row, round row and pipe type.
4. Size specifications: 15cm=6", 20cm=8", 25cm=10", 30cm=12".