This flap is composed of double-walled Lexan (polycarbonate) segments with flexible joints between them. So, on the one hand, it's extremely chew resistant. Lexan is what bullet-proof windows are made from. But the flap is also flexible which is important for safety.

Since the flap has hollow sections, we expect that it will insulate well or certainly much better than flaps that are simply a thin cross section of vinyl.

And here's an example of excellent foresight on the part of Ideal: The sizes have been chosen so that these pet doors may be retro-fitted in existing Ideal 'Original' Medium and XLarge size which we would highly recommend if you are at all unhappy with your current performance.