Perfect Pet Deluxe Telescoping Pet Door Pet door that features inner telescoping frame that adapts to doors of 1/2 In. to 1-3/4 In. thickness. Includes high-quality aluminum construction, and a clear flap to allow pet to see if slide isn't in place. Features tamper-proof mounting so that the door can't be removed from outside and a Thermo-Insulated lockout slide. Installation measurements is the opening you cut in the door to install. How to select the right pet door Step 1 Measure your pet from the top of the shoulders to the chest, just behind the front legs. Step 2 Determine your pet's weight. Step 3 Select the correct door size based on your pet's measurements and weight. Opening Size 15 In. x 20 In., Pet Size 91 to 120 Lb., Material Aluminum, Color White, Lockable Yes, Thickness 1/2 In. to 1-3/4 In., Cut Out Dimensions 15-1/2 In. x 22-3/8 In., Pkg Qty 1, Package Type Box