The Ideal Deluxe Pet Door is ideal for those who prefer a strong high quality telescoping aluminum frame pet door with Lockout Slide. Tamper-Proof Mounting System door can"t be removed from outside. Flap size - 10.5 x 15 inches. External frame - 12.75 x 18.625 inches. Recommended for pets up to 70 pounds. Inner telescoping frame adapts to all hollow core and solid doors of 0.5 to 1.75 inch thickness. No need to build an inner frame. High quality aluminum construction. Clear flap allows your pet to see if the slide is in place. Tamper Proof Mounting System - door can"t be removed from outside. Thermo-Insulated Lockout Slide