This chew-proof aluminum dog door is made especially to either complete your handmade dog house or finish a professional kennel building. The door is spring loaded, so that when the dog pushes out, the door closes automatically. The flange on the edge of the door allows your dog to use his snout to push the door back open to go inside. Ventilated for summer yet protective for winter. There’s also an added training bonus of a loud slap when the door opens and closes, perfect for de-sensitizing gun dogs to noise. The door is 12 in. wide by 17 in. tall and is sold separately from the door frame. Will cover a maximum opening of 11"x16", but smaller opening can be covered. Please specify left or right hinge placement when ordering.