Ideal Ruff Weather pet door flaps need to be replaced every few years. The Ruff Weather doors come with 2 flaps, one in the inside frame, another on the outside frame. The flaps are sold individually. Ideal changed the way they listed the extra large flap size. They originally called them 9 3/4 x 17, then later changed it to 10 ½ x 15. The flap size never changed. If you have an extra large door, the extra large flap we sell will fit, regardless of what it says on the flap when you receive it.