Flap Dog Door Size Small Door flap only, dog house sold separately Indoor/outdoor house for dogs up to 35 pounds Ventilated and insulated for year-round comfort Maintenance free; snaps together in minutes; easy cleaning with built-in drainage hole Exterior measures 24 by 25 by 251/2 inches; interior measures 17-1/2 by 17-1/2 by 20 inches Door measures 11 by 15 inches (width by height)