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uPVC panels are a durable and long-lasting alternative to composite doors. They are strong energy efficient, durable, and fireproof. They are also reasonably priced and easy-to-maintain. Ordering a double-glazed sealed unit with an opening already cut for the cat flap is the simplest method of installing a cat flap in a uPVC sheet. This is more secure than cutting a hole through an existing glass panel. UPVC Doors