The Louvers are made up of strips or individual horizontal panes of glass that are attached on the sides to the window frames. The glass can be tilted open by rolling the lever, or handle, and the panes tilt up from their vertical position to allow air through, while still keeping out rain and other external elements. Side window and quarter window louvers and covers come in ABS plastic, fiberglass, urethane, acrylic, and for select applications. They are an attractive way to provide privacy and security while allowing for the free flow of air. Louvers are very effective.