Product DescriptionExternal size (L x W x H): 19 x 21.5 x 5.5 cm Internal size (L x W x H): 16 x 15.7 x 5.5 cm It is suitable for cats weighing less than 7 kg and at a waist circumference less than 40cm. Note: 1). Make sure the width and height (at the shoulders) of the animal are less than the pet screen door, thank you. 2) The magnet at the bottom of the door frame is for align pane after moves, it doesn't work as a lock, thanks. Product Enhanced Features: 1. Convenient button-style switch, you can easily control your chat or other chat input or output options, only at your fingertips. the entrance, at the entrance, at the entrance and at the entrance. exit, totally locked. 2. The fixed groove with tabs to agrave; pressure for a weatherproof brush strip greatly helps to fix it. 3. The depth of the tunnel can be reduced, plus 1 pack of long + 1 pack of short screws, double-sided adhesive tape, to meet the needs of the tunnel. your needs, which install in various types of interior doors, exterior doors, walls, windows, closets, glass, etc.Installation instructions1. Trace the outline on the door Draw the frame for the cat door on cardboard and cut it out. Use a pencil drawing around the edge of the cut paper. on the door on which you wish to be fixed. Note: 1. You'd better prepare these necessary tools first: pencil, cutter, electric saw, drill, screwdriver, double-sided tape. 2. If you can directly draw the outline of the outer door frame with the product itself, it is fine.2. Cut a tunnel hole First drill 4 corners for the deep holes with an electric drill, then cut out the tunnel hole with an electric saw starting with the drilled holes. Note: Generally, the average installation height is about 10-15cm from the floor.3. Reduce the depth of the tunnel if necessary If the cat door is too thick for your door, use scissors or a machine cut to cut part of the tunnel along line A or B. The cut scale is about 2-4CM.4. Wrap the tunnel hole Once the tunnel is dug, it is best to wrap it with a layer of wood skin.5. go up to the door Mount the cat door with double-sided tape on the door. 8 screws were removed. provided for your use, tighten them with a screwdriver on both sides. Note: 8 screws for 4 holes on both sides, screw them all in 2 sides as shown. above, please. These 8 screws are designed to work together, they are not short.6. Done Put the caps on. screw on the screw holes, press it. Installation is complete.