This type is developed for doors requiring airtightness for business-use ovens, freezers/refrigerators, prefabricated freezers/refrigerators, industrial large-type ice machines, medical equipment, inspection/testing equipment, doors for drying, refrigerators with freezer, container vehicles, food wagons. The walk-in and roll-in types are provided with the unlockable function for emergencies, such as escape from a locked-up storeroom, or with a key or padlock to prevent robbery of quality food materials.