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It is possible to fit a cat flap in the door panel made of upvc or double glazing glass sealed unit, although the best option is to buy a new glass pane with an already-made hole. Read the instructions that should be included in the kit for cat flaps, and follow them closely. Make sure the shape you've drawn (be it square or circle) is accurately depicted on the template. Safety A microchip-activated pet panel inside your door made of upvc is a great option if you have a dog or cat and would like to let them out into the garden, but