L Size: outer frame: 33 x 44cm, inner door flap: 28 x 33cm, S Size: outer frame: 25 x 31.5cm, inner door flap: 21 x 24.5cm, The pet door is made of high quality material, it is wear-resistant, temperature resistant and has a long service life. COMFORTABLE FOR DAILY LIFE: Ideal for balcony doors, so owners don't have to open the door again and again for their pets. Open a separate entrance / exit for pets and this does not affect the normal use of the fly screen door after installation, which also provides protection from mosquitoes and insects. Easy to use: magnets in the bottom of the frame, close automatically; the item is lightweight, and you do not need any effort for pets to open, and it is very easy to understand how to use; the locking locks on the left and right side of the door allow full locking of the door and control the access of the pet. Suggestions: pet flap is suitable for fly screen doors, windows and other fly screen areas; installation instructions for easy installation is included; inner flaps do not include grid, you need to install the cut out grille in the frame of the cat door.