3 Flaps & super sealing: On the basis of the original double flap with superb insulation and sealing, we have added a new thermal insulation layer design, adoption of new insulation materials, which brings stronger thermal insulation, sealing effect, and better isolation of cold & hot air from entering. In addition, with the fur strips on the side and the super strong magnet on the bottom, it can achieve better adsorption and isolation of dust, wind and insects. Large Dog Door Size: VOSOIR Large dog door features a spacious 18.7 x 9.92 inch flap opening. It is suitable for large dogs weighing up to 110 pounds. When you make a hole in the wall, the opening in the wall measures 10.6 x 18.9 inches. And it features an expandable channel that can accommodate walls ranging from 3.95 to 7.5 inches thick.