4 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 --- M: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 than40cm L: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 than60cm XL: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 than75cm SAFE & 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.