The cat flap can be set to four modes with a flap switch: exit only, entry and exit only, and fully locked, making it easy to control your pet's access. This flap has a special seal and a magnetic design to effectively prevent drafts. The transparent flap allows you to clearly see your pet through the opening. This cage is suitable for windows, doors, cabinets, panels, and walls, and can be installed on doors and walls that are 2 to 5 cm thick. Size: S: Outer dimensions: 20 x 19 x 2.1 cm, inner dimensions: 14.5 x 15.5 cm, suitable for pets weighing less than 4 kg and with a chest circumference less than 20 cm; M: Outer dimensions: 19 x 20 x 5.2 cm, inner dimensions: 15.5 x 14.5 cm, suitable for pets weighing less than 5 kg and with a chest circumference less than 40 cm. L: Outer dimensions: 23.5 x 25 x 5.2 cm, inner dimensions: 18 x 19.5 cm, suitable for pets weighing less than 6 kg and with a chest circumference less than 60 cm; XL: Outer dimensions: 28.5 x 24.5 x 5.3 cm, inner dimensions: 22 x 22 cm, suitable for pets weighing less than 12.5 kg and with a chest circumference less than 75 cm. The cat flap is made of weather-resistant ABS, smooth and durable.