The pet doors are made of high-quality ABS material, durable, sturdy, and easy to clean. They are ideal for wooden doors such as interior/exterior doors, doors and windows, and closets. 4 Switching Modes: The pet door can be set to 4 modes: just out, just in, out, and fully closed, to easily control pet entry and exit. Construction Details: The cat door's sealing brush strip can reduce noise when closing the pet door. The cat doors are well sealed to prevent rain, wind, or pests such as mosquitoes from entering the home. Inner door opening dimensions: 18 x 18.5 cm, outer frame dimensions: 23.5 x 27.5 cm, maximum thickness: 5 cm. Suitable for small dogs or cats so they can come and go freely.