"For those that live in areas with an extreme climate, the PetSafe Extreme-Weather Pet Door was made for you. The unique three-flap system keeps hot and cold weather out of your home while still letting your pet come and go as they please. Snap-on closing panel is included to allow you to control your pet's access. Additional closing panel (not included) can be used on outside for additional protection. Imported. Available: Small (11""H x 7-1/2""W frame, 8-1/4""H x 5-1/8""W flap) Medium (15""H x 10-1/2""W frame, 12-1/4""H x 8-1/8""W flap) Large (19-7/8""H x 12-1/2""W frame, 16-1/4""H x 10-1/8""W flap)"