A screen for a patio window

My porch windows are in three parts-top pane , bottom pane and And screen. All three parts slide up and down in their own tracks. You can slide into different open positions because there are latches cut into the frame. I think the frames are aluminum but strong. My screen is broken. It is 25 inches long and 18 inches wide. There is a number on the screen A-X7164. I am looking to get a new screen.