A cat flap is basically a hole that you can insert into your door so that your cat can leave and come whenever they want. This design isn't very secure and could provide easy access for burglars. You should consider upgrading to a home that is lockable or automated, with https://catflapdoubleglazing41986.onzeblog.com/30805190/using-a-cat-flap-in-bifold-doors