Impact-resistant white plastic frame that adapts to doors ranging from 1-1/4" to 2” in thickness Flexible vinyl flap with patented edges that won’t warp from use or extreme temperatures Floating bottom threshold for perfect seal every time Lock-out slide to keep your Ideal Pet out of mischief when unsupervised Average install time: 20 minutes To determine the correct size door, simply measure the width (A) and height (B) of your pet. (A) Measure the widest point of your pet's shoulder. (B) Measure from the top of your pet's back (just behind their head) to the bottom of chest. Pet door models have different size openings. Just make sure your new pet door's opening is both wider and taller than your pet's measurements to ensure they can comfortably pass through.