Built for dogs that have outgrown a small flap, this sliding glass pet door has a 10 1/4 x 16 1/4 inch opening that comfortably fits small to medium breeds while still sliding neatly into your existing door track. Setup takes minutes: the aluminum frame and tempered glass panel adjust to door heights from 75 7/8 to 80 11/16 inches, so there's no need to measure and cut a custom frame. A metal cover around the flap resists scratching from daily use, and the hinge is engineered to stay flexible in cold weather rather than seizing up when temperatures drop. The lock lets you close off the opening whenever you want your dog kept indoors, whether that's at night, when you have visitors, or during bad weather. Weighing 17.9 pounds, the door is manageable for one person to install and remove, which makes it a good fit for apartments and rentals where a permanent pet door isn't an option.