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It is possible to install a cat flap in a door panel made of upvc, or a double glazing glass sealed units however the best choice is to have a new glass pane that has an already-made hole. Read the instructions that should be provided with the kit for cat flaps, and follow them closely. Make sure the drawing accurately represents the shape (circle or square). Safety If you have a dog or cat and want to let them in the garden without having the door open, a microchip-activated pet flap in your door panel made of upvc is a fantastic opt