Suitable for most turbine ventilators: The size of the roof ventilator cover is 20 inch x 20inch. Please note the dimensions of the turbine fan. Protection function: after installing the roof ventilation cover. It protects the turbine from rain, snow, wind and dust. Protection of indoor environment Hygienic environment. Prevent heat loss by reducing the indoor temperature. Waterproof and dust-proof: the roof ventilation hood is made of 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. Colour:black Material:polyester Size:51x51cm Package Contents: 2 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 picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.