About this item4 WAY SWITCH 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 SIZE & APPLICATION ---S:Outer Size: 19*19 7*2cm(W x H x D), Inner size: 16*15 7cm(W x H),suitable for installation on doors and thin walls, suitable for cat and doggie lighter than 4kg and waist circumference shorter than25cmM:Outer Size: 19cm*20cm*5 5cm(W x H x D), Inner size: 15 7cmx 16cm(W x H),suitable for installation on doors and thin walls, suitable for cat and doggie lighter than 5kg and waist circumference shorter than40cmL:Outer Size: 23 5*25cm*5 5cm(W x H x D), Inner size: 18cm x 19cm(W x H),suitable for installation on doors and thin walls, suitable for cat and doggie lighter than 6kg and waist circumference shorter than60cmXL:Outer Size: 25cm*28cmcm*5 5cm(W x H x D), Inner size: 20cm x 22cm(W x H),suitable for installation on doors and thin walls, suitable for cat and doggie lighter than 12 5kg and waist circumference shorter than75cmSAFE & THOUGHTFUL --- The transparent flap let pet see through the door Exterior rain seal is for waterproof Brush strip eliminates noise from the door closing EASY TO INSTALL --- Complete instructions included, make you easily install in windows, doors, cupboards, panels and walls etc EXCELLENT QUALITY --- Made of ABS material, weather-resistant, the surface is smooth and durable