Google is your friend. Found this.
Window Visors:
Have you ever wanted to crack your windows for fresh air, even in driving rain? How about leaving your car parked with the windows open and not having to worry about rain? Both of these are possible when you?re protected by window visors. Window visors, or rain guards as they?re sometimes called, are the aerodynamic covers that hang over your window opening. They allow you to open your windows a few inches without rain or water coming in. They also cut down on wind noise and turbulence that typically accompany open windows on the highway.