https://www.openlearning.com/u..../andreassenkirby-skr
https://day-wise.hubstack.net/....fitting-a-cat-flap-i
A cat flap made of UPVC lets your cats go and go as they please. The installation is a three-step procedure that can be performed on wooden doors, glass panels or UPVC panels. This is a great choice for those who want to secure their pets and save on energy costs. UPVC panels are resistant to moisture, heat, and UV. Easy to install Installing a pet flap onto your glass door or window is a great idea if you have a cat.