CONVENIENT LOCKING --- Knob style knob is rotatable in 4 directions. You can easily rotate it in 4 modes with the arrow and icons to control your cat's access options: entry only, exit only, free entry and exit, totally locked. WEATHER RESISTANT WATERPROOF BRUSH STRIP --- It offers a fixed groove with snap tabs for a weather resistant brush strip. Even if the brush strip comes off, it is easy to put it back in the fixed groove. This greatly helps the brush strip to reduce noise, keep out raindrops, wind or pests like mosquitoes. SCREW KITS --- It comes with 2 packs of 8 screws each, one is filled with short screws, the other is long. Screw them with both sides to avoid cracking, don't just one side. You can make 8 screws for the 4 screw holes with long+long, long+short or short+short groups depending on the depth of the door/wall being installed. EASY TO INSTALL --- Step-by-step installation instructions in the installation manual included in the sales box and the installation overview video. The depth of the tunnel can be reduced depending on the needs of your installation. APPLICABLE FOR --- Inner size (L x W x H) 18 x 19.5 x 5.5cm, it is suitable for cats whose waist circumference is less than 60cm. And the outer size is (L x W x H) 23 x 27 x 5.5cm. It is suitable to be installed on interior doors, exterior doors, walls, windows, closets, glass, etc.