1.This pet door can be a great way to monitor your pet and free up your time to open the door without worrying about your pet. At the same time, your pet will enjoy a large free house, preventing unwanted animals from entering your home 2.Easy Installation - This pet door is suitable for brick walls, wooden doors, doors PVC and metal glass doors, and can be installed on 2-5cm thick doors and walls. The cat flap is made of durable, weather-resistant and easy-care ABS plastic 3.Unique design: Use the cat flap with 4 locking options to get cats up and down at will, or to keep them safe home or away. Closing options are: open in, open out, open both ways, closed 4.High quality ABS plastic materials, durable, scratch resistant for your cat/small dogs. Whats more, it is easy to clean and can be used for a long time 5. M: 19.7*19*5.5cm, pet under 10kg, waistline under 40cm L: 25*23.5*5.5cm, pet under 12kg, waistline under 60cm XL: 27.7*25*5.5cm, pet less than 25kg, waist circumference less than 75cm