Provide your pet with convenient entry and exit with our pet door. Soft and flexible double flap features strong magnetic closure, can effectively save energy. metal panelattached slider, helps protect against extreme weather conditions. And keep your home safe when the door is not in use. Specification: Material: ABS Size M: External Size: Hight: 20CM Width: 19CM Thickness: 5.5CM Inner Size: Hight: 16CM Width 15.7CM Weight: 0.34kg Suggested weight: Weight ≦ 14KG Height ≦ 40cm M: 19.7195.5cm, pet under 10kg, waist circumference under 40cm L: 2523.55.5cm, pet under 12kg, waist circumference less than 60 cm XL: 27.7255.5cm, pet under 25kg, waist circumference under 75cm How to install 1.To find a door and draw a square according to the size of the flap 2.To drill 4 holes in the four corners with an electric saw 3.To cut the square, and insert the flap of the cat into the hole (If the tunnel is thicker than your door, you can cut it according to your needs) 4.To screw the cat flap