Tempered safety glass panel - Lockable 4-Way Lexan Flap (Keeps pet in or out) - Aluminum frame - Spring loaded adjustable width - Requires window channel track width of at least 15/16" (panel thickness). Measure your window track width before ordering. This panel requires a window width of between 19" and 24" (not recommended for window widths less than 19.5"). Easy Installation (Instructions Included Inside Box) Lockable 4-Way Lexan Flap (Keeps pet in or out) Tempered safety glass panel Weatherproof design with draftstopper (Weather stripping and foam bumper included) White finish