You know that dog doors are convenient. No getting up in the middle of the night to let your dog in and out, no interruptions during dinner, and no need to worry if you can't get home from work right on time. But pet doors are not only convenient for you, they're actually good for your dog! By giving you dog the freedom to move in and out, a number of common behavior problems can be eliminated. PetSafe dog doors are a safe and convenient way to improve your dog's behavior, but your job doesn't end with installation. All dogs need proper training in how to use the pet door and in basic obedience. A free video is included with every PetSafe pet door to help you train your pet and install the door. PetSafe AF50-201-11 Classic Pet Door Features: Dog Size: up to 220 lbs Flap opening: 13.875" x 23" ULTRASEAL all weather, energy conserving flap system reduces energy loss in winter and summer GRIP-TRAK insulated, locking security cover is the strongest and most secure available Soft transparent single flap for maximum energy efficiency Heavy Duty aluminum frame built to withstand the stress from even the most powerful breeds Telescoping adjustable frame creates its own protective inner frame in doors for 1/16" to 2", may also be installed in walls but additional framing is required Adjustable sill with extra strong magnets hold the flap in place for a tight weather seal Insulating, non-rusting security cover has dual locking pins (except small) to prevent removal of the security cover from the exterior See-through flap design aids in training Easy-to-follow installation manual Installation and training video included Lifetime Warranty