CONVENIENT LOCK --- The button-style switch is 4-way rotatable, you can easily rotate it into 4 modes with the arrow and icons to control your cat's access options: in only, out only, in and out freely, fully locked. IMPROVED WEATHERPROOF BRUSH STRIP --- It provides a fixed groove with pressure tabs for weather resistant brush strip, fix the brush strip firmly. Even if the brush strip comes off, easy to put back in the fixed groove. This greatly helps the brush strip to reduce noise, stop raindrops, wind or pests such as mosquito the most. THOUGHTFUL SCREWS --- It comes with 2 packages of 8 screws each, one is packed with short screws, the other long. Screw them on from both sides to avoid tearing from incaution, not just one side. You can make 8 screws for the 4 screw holes with long + long, long + short or short + short group, depending on the depth of the door/wall being installed. EASY TO INSTALL --- Step by step installation instruction in the manual included in the sales box and installation presentation video for you reference, provide notice and prepare necessary tools, easy to install as your need. The tunnel depth can be reduced based on your installation requirement. APPLICABLE TO --- Inner size 2.17"/5.5CM(D) x 6.18"/15.7CM(W) x 6.30"/16CM(H), it is suitable for cat with waist circumference shorter than 15.75" / 40 CM. And the outer size is 2.17" / 5.5CM (D) x 7.56" / 19CM (W) x 8.46" / 21.5CM (H). It fits for installing interior doors, exterior doors , walls, windows, cabinets, glass, etc.