Horizontal Slider windows open with the sash sliding left or right. Some people find a sliding glass window easier to open and close than a crank-style window. Since they slide open without protruding, horizontal sliders are an excellent choice for rooms facing walkways, porches or patios. Horizontal slider windows are a favorite for contemporary style homes and are also popular for satisfying bedroom egress requirements. In a single slider, one sash slides to open. In a double slider, both sashes open, which can be great for providing air circulation to a room.