So, either heating or cooling the back yard with an old fashioned pet door just won't do anymore. In some cases the energy waste is like opening and closing the door itself 4 or 5 times a day.

Perfect Pet has the answer with The Rough Weather/All-Weather Door's air pocket between 2 soft flaps, making it a great energy efficient insulator.

The All-Weather (rough weather) series in Small, Medium, Extra Large and Super Large are designed to give an air pocket of up to 3 inches between the 2 flaps in a door installation. And with the available wall tunnel kit, an air pocket of up to 9 inches. This is serious energy efficiency. (Also see the wind resistance tests below)

Magnador Pet Door Features:
• Easy installation.
• Nylon lock security system for strength and long wear.
• Molded-in weather and insect protection
• Limited one year warranty.

Large door size: Frame approx 18" x 24", flap approx 13" x 20"

Actual pet door Flap Dimensions:
Small: 8"H x 5.25"W
Med: 11.75"H x 8.5"W
Med/Tall: 16"H x 8.5"W
Large: 16"H x 10.4"W
XLarge: 23"H x 13.75"W

Details

The NEW Pet Safe doors have a "floating magnet bar". The OLD Pet Eze have a manually adjusted bar. (The magnet bar is directly underneath the flap. Its magnets attract the magnets in the flap.) The magnet bar is about 1/2" wide and usually sticks up about 1/8" higher than the rest of the frame. (At first glance it looks like the frame is all one piece, but it isn't; the center part moves.) Over time, the manually adjusted bar drops too low.