US Patent 7063123 Adjustable pet door

A panel pet door is an insert into a sliding glass door and has a panel door frame and a movable door flap assembly mounted on the panel door frame. The door flap assembly can slide vertically on the panel door frame along tracks in the vertical stiles of the panel door frame. A plurality of riser spacer panels are also mounted on the panel door frame and are also vertically slidable on the frame via the vertical tracks. The door flap assembly and spacers are selectively removable and replaceable to effect a change in the rise of the door flap assembly and the height of the door flap assembly.