This pet door installs directly into your sliding glass door track, so there's no cutting into the frame or hiring a contractor, the aluminum frame and tempered glass window simply slide in and adjust to fit door heights between 75 7/8 and 80 11/16 inches. The 8 1/4 x 12 1/4 inch flap is sized for small dogs and cats, giving them easy in-and-out access while you're busy or away. A metal cover reinforces the flap opening for durability, and the hinge is built to keep working smoothly even in cold weather, so the flap won't stiffen up or crack on frosty mornings. When you need to keep your pet inside, overnight, during a storm, or when guests are over, the built-in lock secures the opening in seconds. At 16.3 pounds, the whole unit is light enough for one person to install without tools, making it a practical option for renters who need a door that comes back out cleanly when it's time to move.