Give your cat the freedom to come and go as it pleases 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 cannot come out Cat can exit but cannot enter (to prevent other cats from entering) also enter) The flap is locked on both sides The flap is completely open and the cat can come and go at will The cat flap is easy to install and is suitable for n any wall or door up to 50mm thick. Also suitable for small dogs/cats. Features: Size: S19*19.7*2cm M19*19.7*5.3cm L25*23.5*5.3cm XL :25*5.5*27.7cm(please measure your pet before ordering ) The 4-way cat flap is brand and boxed Material: hard plastic installation method: Needed tools : 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 a few millimeters error); Step 2: Finish the drawing and mark it on the door and draw the seal with a pencil; Step 3: Use a drill to drill a hole in the four corners of the painted door, then start digging the hole directly if there is a chainsaw; Step 4: If it is a glass door, use a glass scribing tool to gently pry it open and secure it with glass glue. Step 5: The hole is cleaned, now first get a layer of wooden leather to wrap around the hole, for the sake of beauty; Step 6: Install the cat flap, there are accessory screws and screw them with a screwdriver; Step 7: The screw port is also equipped of a screw lid, press it, OK, done Package included: 1 x flip-up pet door