Carlson Pro Pets Wall Mount Champion Pet Door, Medium Double pane Lexan flaps provide insulation and allow the pet to see through the door Training tool provided to acclimate your pet to its new door Features security lock and quick attach stainless steel security panel Incredibly easy installation, expandable tunnel in wall mount version fits walls from 4.75 Inch to 8.25 Inch with no cutting of the frame required Medium Opening Dimension 16"l x 10"w