Check out this video for more information on Sunspace Horizontal Roller windows.
The WeatherMaster window also comes in another version: the horizontal roller.
It allows for up to 50% ventilation vs 75%. But the windows can easily pop out and can be stored away for 100% screen. They pop right back into place as easy as this. They lock into place. They have brass rollers on the bottom that are guaranteed forever. The weight of this window is probably a tenth of what a glass window would be.