A door-mounted Hale Pet Door is one of the easiest pet doors to install yourself. These pet doors can be installed through wood doors, metal doors, hollow core doors, and raised panel doors. They can also be installed in French doors but you will likely be better off with professional installation in that instance.
Hale Pet Door models for doors are available in 11 standard sizes and four standard colors. They come standard with a single flap but you can opt for a double flap (for an additional charge) if you live in a region with extreme temperatures or winds. A flap on the outside and a flap on the inside can make a big difference in minimizing loss of heat or air-conditioning through a pet door.