Large Dog Door Size: Our premium large dog door features expandable channels to fit doors or walls from 1.26 to 2.08 inches thick. The flap opening measures 18.7 x 9.92 inches, perfect for medium-sized animals weighing up to 110 pounds. Please carefully review the size chart in the fifth and sixth picture and confirm if the size is suitable before purchasing. VOSOIR all-aluminum alloy dog door: the whole dog door is made of full high-quality aluminum alloy, reinforced by higher-end welding process to make it more solid. Compared to the market plastic dog door durability greatly improved; compared to the market iron pet door, non-pure aluminum alloy dog door (plastic frame and aluminum alloy combination) is more solid and not easy to deform and rust, paint does not flake! Energy Efficient: We use the latest PA material, the brown and black translucent panel protects against UV rays, isolates hot and cold air more efficiently than traditional flaps by more than 50%, and can cope with extreme weather more effectively. Improved magnetic closure technology and high-density dust strips provide a stronger seal, which not only resets the baffle better, but also effectively prevents dust, insects and wind from entering.