https://digitaltibetan.win/wik....i/Post:How_to_Train_
Cat flaps allow your pet leave and come whenever they want, without you having to let them in or out. They also prevent your cat from urinating inside the house. Fitting a cat flap in a upvc door panel is a lot easier than a glass door, however it does require some skills and the proper tools. Measure the Door The installation of a cat flap inside a door can be tricky but as long as you use the correct type of cat flap, take your time and follow the directions provided, it should not prove to be too difficult.