Some older homes, cottages and apartments have windows without insect screens. If yours is one of those, you can protect your home with this adjustable window screen. It works best with double-hung windows - the kind with a lower half that slides up and down. The window screen fits into the side channels when the window is open. The lightweight and durable aluminum frames will never rust. Simply adjust the width to fit your window, push the window panel up and slide the screen into place.