https://www.openlearning.com/u..../whitemitchell-sm4p5
You're tired of having to stand up to open the door to your pet. A cat flap could be the solution. Pet-flap fitters are able to install them in any type of door, including uPVC or composite doors. They can also be installed in a variety of wall types. Security Cat flaps are usually used to cover doors, however many people also have them installed on windows or double-glazed doors. The installation of a cat flap into glass can be a good option for those who don't want to cut through a wooden or wall door,