Ultra Flex Energy Efficient Pet Door Medium 6-5/8" x 11-1/4" Flap Size Lexan Flap with 3 Articulated Panels Medium Size Door 6-5/8" x 11-1/4" Flap Size Lexan Flap with Three Articulated Panels Fast & Easy Installation Frame Adjusts to 1" - 1-3/4" Door Thickness Energy Efficient