12-7/8" x 19-3/4", Large, White, Pet Door, Solid Aluminum Construction, Locking Panel, Transparent Single Flap For Weather Tight Seal, Easy Do It Yourself Installation, Fits Doors From 3/8" To 2" Thick , Flap Opening Dimensions: 10-1/8" x 15-3/4", Cut Out Size: 10-7/8"W x 17-7/8"H, Great For Pets Up To 100 LBS.