Warm Notice: If you have an old dog door that needs to be replaced, you need to ensure that the cut size of the new dog door is greater than the current size.If your dog's body size is close to the size of a dog hole, we recommend purchasing a larger size to make it more comfortable for your dog to pass through. Cutting Size: Cut out size on the door of the house.Flap Opening Size: Size that dogs can pass through. How to Install Setp1: Measure the distance from your dog’s tummy to the ground, then Mark height (H) on panel with tape or similar Setp2: Using the cutting template card. Mark outline with marker pen. Cut out the opening cutting along the mark outline Setp3: Place a bead of construction silicon around the internal section of the pet door and on the surface around the cut out to provide a weather seal Setp4: Insert the inner and outer frame into the cut out and clamp tightly together. Drill screws in the tunnel to fix it and ensure they are evenly distributed Aluminum Medium Dog Door for Interior and Exterior Door, Pet Door for Small D... [MAVRICPOWER] Aluminum Large Dog Door with 2 Magnetic Flaps, Doggie with 2 Sl... Steel XL Dog Door with Two Sliding Lock Panels, Two Magenetic Flaps,... Cat Door for Extreior Door,Small Cat Door with Two Sliding Lock Panels, Two M... Dog Door for Screen Door,Small Dog Door with Lockable Magnetic Flap, Easy Ins... Mavricpower Replacement Pet Door Flap, Easy to Install, Compatible with Alumi... Add to Cart Add to Cart Add to Cart Add to Cart Add to Cart Add to Cart Customer Reviews 4.4 out of 5 stars 28 4.4 out of 5 stars 28 5.0 out of 5 stars 1 — — — Price $79.95$79.95 $119.95$119.95 $179.95$179.95 $69.95$69.95 $36.39$36.39 $35.99$35.99 Flap Double Flaps Double Flaps Double Flaps Double Flaps One Flap One Flap Fits Thickness 1 3/8'' - 2 1/8'' 1 3/8'' - 2 1/8'' 1 3/8'' - 2 1/8'' 1 3/8'' - 2 1/8'' 1 3/8'' - 2 1/8'' 1 3/8'' - 2 1/8'' Sliding Lock Panel Two Two Two Two NONE NONE Weatherproof ✓ ✓ ✓ ✓ no data no data