https://aiwins.wiki/wiki/Fitting_a_Cat_Flap
A cat flap on a door allows your pet to enter and exit the house without having to open it. The doors are available in various sizes to accommodate both cats and dogs. They also come with features that stop draughts and unwanted animals. Introduce your pet to the door before installing it. It will be easier to familiarize them with the shape, size and movement. Easy to install Cat flaps can be put up everywhere You can put one on your garage door or laundry room to give your pets access to litter box and cat food and even on your bedroom door