Material: The cat door is made of ABS material, weather-resistant, the surface is smooth and durable. 4 Lock Options: Customize your cats access with 4 locking options; locked, unlocked, enter-only, exit-only. Safe: 4 way locking of the big cat door meets cat's daily need. The cat flap door with magnet that let the flap can be quickly reset when the cat passes. Inner frame edge of the cat interior door get polished, so as not to hurt cat. Easy To Install : The cat doors for interior doors have detailed installation steps, this cat door can be installed easily in a short time. 8 screws and its caps included in the set make you easily install in doors, cupboards, panels and walls, etc Gives Your Pet Freedom: Let your cats and dogs come and go on their own schedule perfect for potty breaks or play time. SIZE: S-outer size: 19cm*20cm*5.5cm(W x H x D); inner size: 15cmx 16cm(W x H); suitable for cat and dog lighter than 7kg and waist circumference shorter than 40cm M-outer size: 23cm*25cm*5.5cm(W x H x D); inner size: 18cmx 19cm(W x H); suitable for cat and dog lighter than 8kg and waist circumference shorter than 60cm L-outer size: 25cm*29cm*5.5cm(W x H x D); inner size: 20cmx 22cm(W x H);