Size: pet door outer frame: 25 cm x 31.5 cm, inner frame: 21 cm x 24.5 cm. Suitable for small and medium sized pets. Sturdy and durable: the frame is made of high-quality ABS material and attached with reinforced screws for easy installation. With a swivel design, it is careful not to damage the swing door. Easy for daily life: Ideal for balcony doors, owners do not have to constantly open the door for their pets. A separate entrance / exit for pets does not affect the normal use of the door after installation and also serves as mosquito and insect protection. Easy to useThere are magnets on the bottom of the door frame to close it automatically; the element is light enough to not disturb your pet, and it is easy to understand how to use it; there are locks on the left and right side of the door to fully lock the door and control the access of your pet. RecommendationThe pet stopper is suitable for fly screen doors, windows and other shielded areas; the inner stopper does not include the grille, you need to install the cut out grille inside the frame of the cat door.