4 Way Locking Mode --- The pet door could be adjusted by the Red and Green switches with tabs to 4 modes: out only, in only, both in and out, and fully locked, easy control of your pet's in and out. High Quality --- Made of ABS material, weather-resistant, the surface is smooth and durable. It provides a fixed groove with snap tabs for weather-proof brush strips, and firmly fixes the brush strip. Even if the brush strip comes off, easy to put it back into the fixed groove. This greatly helps the brush strip reduce noise, and stop raindrops, wind, or pests like mosquitoes to the most. Easy to Install --- Step by step installation instruction in the instruction manual included in the sales box and installation presentation video for your reference, take care of notice and prepare necessary tools, easy to install as your need. The tunnel depth could be cut down according to your installation need. Applicable scene --- It fits to being installed on interior doors, exterior doors, walls, windows, cupboards, glass, etc. Size & Application --- suitable for installation on doors and thin walls, suitable for cats lighter than 17.64 lb and waist circumference shorter than 23". SIZE TABLE: S: Frame size: height 20*width 19*thickness 2CM Door cover size: inner height 15CM* inner door width 15CM M: Frame size: height 20*width 19*thickness 5.5CM Door cover size: inner height 15CM* inner door width 15CM L: Frame size: height 25*width 23.5*thickness 5.5CM Door cover size: inner height 19CM* inner door width 18.2CM XL: Frame size: height 28*width 25*thickness 5.5CM Door cover size: inner height 22CM* inner door width 19CM