https://wifidb.science/wiki/Fitting_a_Cat_Flap
Installing a cat flap onto a door allows your pet to come and go whenever it wants. Follow the steps to learn how to draw the shape, then use an jigsaw, or a hole saw to cut it and install your cat flap. You can keep wild animals, pests and stray cats from getting into your cat's enclosure when it is equipped with a Manual Four-Way Lock. You can also store plant pots for your cat to nestle in. Placement A cat flap is not just a means for your pet to go outside more easily, but it could also keep unwanted animals such as rodents and cats aw