https://securityholes.science/....wiki/Fitting_a_Cat_F
uPVC panels are a long-lasting and long-lasting alternative to composite doors. They are strong energy efficient, durable, and are resistant to fire. They are also inexpensive and easy-to-maintain. The most convenient way to insert an animal flap on a uPVC panel is to order an additional double-glazed sealed unit with a premade hole for the flap. This is more secure than cutting a hole into an existing glass panel. UPVC doors are easy to maintain Unlike traditional wooden doors, uPVC doors don't require frequent painting or sanding.