Many people find horizontal sliding windows easier to open than a crank-style window. This is because they open with a sliding action, either to the left or right, that makes it simple and effortless to let in fresh air and natural light. These types of windows are ideal for rooms that face onto verandahs, porches and patios, or onto walkways or passages. The reason for this is because they open without protruding to the outside. They are available in a single slider, in which only one sash slides to open, or a double-slider, where both sashes open. This is a great option for increasing the air circulation into a room.