A basic cat flap is a hole inside your door that enables your cat to move around according to their own preferences. This design isn't extremely secure and could give access for burglars. You should consider upgrading to a home that can be locked or automated, with improved security features. https://doubleglazingcatflap18849.myparisblog.com/31204436/adding-a-cat-flap-to-your-bifold-doors