looking for: external 10 inch (25cm) square vent with gravity flaps

[MrMajorThorburn]

I have been trying my hardest to find a square external vent 10 inches (25 cm) with gravity flaps to fit over a square exhaust fan hole in my garden office.
Does anyone have any idea where I may get one?

 

[gorgon]

What about cover the hole with a weather resistant board and mount a smaller, and easier to get, vent in the board? This depends on the type of wall covering you have, but you could make the hole smaller with the same material as in the wall.

 

[MrMajorThorburn]

I did not want to reduce the air flow from the 25 cm exhaust fan any more than necessary but I thank you for the suggestion and will keep it in mind as a possible solution.