If you find yourself in a rented home or apartment, or momentarily without a window screen, an adjustable window screen is a perfect temporary or seasonal solution without having to learn how or hire someone to create a permanent window screen. An adjustable window screen is designed to fit into an open window, typically a double-hung or single hung window. They can be adjusted to variable opening widths. Two overlapping screens share a sliding track that enables you to expand or contract the screen to fit any window and the height is usually fixed.