It is possible to put a cat flap into the upvc panel, or even a double glazing sealed unit. However, the best alternative is to install an entirely new glass pane that has a pre-made hole. Follow the directions included in the kit. Ensure that the shape drawn (be it https://doorswithcatflap25632.blogrenanda.com/36748421/how-much-does-a-cat-flap-cost