Protection function: after installing the roof ventilation cover. It protects the turbine from rain, snow, wind and dust. Protect the indoor sanitary environment. Prevent heat loss by reducing the indoor temperature. Waterproof and dust-proof: the roof ventilation hood is made of high-quality polyester. Silver plated inside. Good waterproof effect. Prevent dust from entering the room. Easy to install: The bottom of the roof vent cover is designed with drawcord. Tighten the pull rope to fix it. Prevent the ventilation cover from being blown by the wind. Suitable for most turbine ventilators: The size of the roof ventilator cover is 20inch x 20inch. note the dimensions of the turbine fan. Colour:Khaki :polyester Size: 51 x 51cm Package Contents: 4 x vent cover Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.