https://squareblogs.net/shield....europe1/cat-flap-gla
Installing a pet flap on your French or patio doors is a great idea if you have a dog or cat. It lets them get in and out without having to open the door. There are many cat flaps available to be used with uPVC wood or composite doors. Some have a four way locking system that can be set for exit only, in-only, or open. Installation Cat flaps are an excellent way to let your cat in and out of your home without having to open the front door every single time. This is especially helpful when your cats are keen