https://marvelvsdc.faith/wiki/....Using_uPVC_Cat_Flap_
If you have a cat or dog, installing a pet flap inside your French or patio doors is a great idea. It makes it easier for them to get in and out without you needing to open the door. There are many cat flaps available designed to fit in uPVC, composite, or wooden doors. Some even have a four-way locking system that can be configured to let out only or in the open position, or both. Installation Cat flaps are a great way to let your cat out and in of the home without having to open the door each time. This is especially helpf