This dog door mounts into your existing sliding glass door track, letting an extra large dog come and go without you opening the door every trip outside. The frame adjusts to fit openings between 75 7/8 and 80 11/16 inches tall, so it slots in alongside your existing glass panel without permanent cutting or drilling. Built from aluminum alloy, the frame holds up to daily use from a big dog while resisting the corrosion and warping that can affect painted or plastic frames over time. The flap swings open a full 180 degrees in either direction as your dog pushes through, and it comes with a lock so you can seal the opening overnight or while you're away. Sized for extra large dogs, it gives bigger breeds enough clearance to pass through comfortably, making it a straightforward way to add a permanent pet entrance without replacing the whole sliding door.