a safety device for an automobile such as a car or a van , the safety device being a window insert designed to fit within the standard frame of a window and be retained within the frame by the upper edge of the window fitting within a groove configured on the lower edge of the window insert . the window insert may include orifices to allow air inflow and / or outflow so as to provide a continuous flow of fresh air into the vehicle . the safety device may be used to retain a child or a pet , and can be formed from a plastic , plexiglass or polycarbonate material . alternatively , the window insert may be formed from a high impact or bullet - proof material .