https://nerdgaming.science/wiki/Fitting_a_Cat_Flap
Introduce to the flap prior to installation so that they become familiar with the dimensions and shape. The flap should be opened and let them explore it from every angle. Make sure the cutout is even and square. Mark the screw holes on your door and align them with the opening of the cat flap - the distance between the edges must be equal. Preparation A cat flap in your home is beneficial for the health and well-being of your pet. It will allow your pet to move from the inside to the outside without you needing to allow them in or out