What's it called

I need the term for a kind of coarse net one might place between curtain and window so that when the window is open, the pressure from our air conditioner doesn't blow it out against the window screen on the other side, blocking an airflow that might otherwise keep the room a little cooler

It would of course mount inside against the window opening. I'd imagine it a bit bigger than the typical home window with eg a narrow shelf for support at the bottom. On top I'd imagine using a strip of doublestick tape for instance to hold it against the frame

A more elaborate model might have a shelf clear around its perimeter adjusting to match the frame. If no such thing is made, of course I'd adapt a length of wire fence

Thanks all