Give your cat the freedom to come and go as they please with this cat flap featuring a 4-way locking system. Slide the locks on the bottom of the flap to set the door to one of the following options: Cat can only enter from the outside but not go out Cat can go out but not go back in (to prevent other cats from entering too) Flap is locked on both sides Flap is fully open and cat can come and go as they please The cat flap is easy to install and fits any wall or door up to 50mm thick. Also suitable for small dogs/cats. Features: Size: S：19*19.7*2cm M：19*19.7*5.3cm L：25*23.5*5.3cm XL:25*5.5*27.7cm(Please measure your pet before ordering!) The 4-way cat flap is brand new and packaged Material: hard plastic Installation method: Tools needed: electric drill, iron saw or electric saw, measuring ruler; Step 1: First use a piece of paper to draw the size of the door cover (there may be an error of a few millimeters); Step 2: Complete the drawing and mark it on the door and draw the seal with