Ventilator: Keep the air circulation clean, and install it in the harsh environment such as wall or ceiling interlayer, and the heat dissipation of the motor is limited, or it is easily affected by sunshine, wind and rain. Installed in a high place, it is not easy to be touched by people, and the direct protection requirements are low. Close-fitting installation requires attention to the influence of body vibration; Pay attention to waterproof, dust, sand and sunshine.