The WeatherMaster Horizontal 2 and 4-Track Window System closes to reduce wind, rain, pollen & sound. These units move effortlessly, sliding right or left to allow a generous 50% to 75% ventilation. Designed specifically for porches, screen enclosures or even gazebos, the WeatherMaster system is easily installed and can convert any of these areas into your favorite 3 season room in the house.