Pet Door From Top Pet Choice Ideal For Doors, Sliding Doors and Even Windows That Have A Screen. Your Dog Or Cat Will Love The Easy Access To Go Outside And Inside. Fast simple installation by snapping onto your screen to give pet outside access Compatible with most metal or vinyl coated fiber screen doors, window screens or porch screens Durable frame with screen flap to blend with existing screen. Flap opening size is 30 cm width x 40 cm height. Measure your pet to ensure this pet door is the right size for your pet. Flap locks to prevent your pet from using the door during unwanted times Installation instructions included