According to the fire resistance of steel fire doors, different grades of steel fire doors can be used in various places.

https://ztfiredoor.com/23905.html

steel fire rated entry doors,4 fire doorsnominal fire door rating,sliding fire doors domestic,1 hr fire door,fire door inside,steel fire rated entry doors,60분 화재 등급 다락 사다리,sliding fire doors domestic,불 정격 문 잎,steel fire rated entry doors,창을 가진 불 정격 강철 문,4 fire doors수직 방화문,sliding fire doors domestic,반대로 방화문,4 fire doors내화성 강철 문