https://algowiki.win/wiki/Post:Fitting_a_Cat_Flap
Cats love looking out of windows, a pastime often known as cat television. It's a form of entertainment that is often instinctive. Glass window inserts that have the cat flap can be fitted to existing windows or doors. They can be put in double glazing. Easy to install Cat flaps can be affixed to a variety of glass including french doors, patios, bifolds and single-glazed windows. They are perfect for those who aren't keen on cutting into a wall or door and want to give their pet to access a window. However, be aware that fitting an ani