BEST Pet Door for Sliding doors, Lightweight plastic Insert designed for easy of use.  It's Foldable and Frameless Pet Opening is perfect for Dogs and Cats.  Helps to keep your old dogs independent.  NO Tools, Held in with a Hook and Loop System (velcro). Stays up even when opening and closing your sliding door or screen.  Made for Standard Size 80" tall Sliding Doors and easily modifiable for shorter than standard door heights.