composed of strong frames made of stainless steel plate ,with nonflammable&nontoxic infilling material,fire resistant glazing and fireproof hardware,are able to withstand the hash test of fire ,around 1000C flame,fore a few hrs keeping stablility ,integrity &insulation of the door sets,and stop the quick spreading of flame and smoke.they can protect people &property temporaily from the threat of fire and win the most precious escaping time .boan high quality products ensure the ideal application in customers's building