Overview of smoke shielding and fireproof double doors: when the size of the door opening is large (more than 3 square meters), and the rotation track of the fireproof door will hit the wall or partition wall, use 2 or 3 folding doors to reduce the rotation track. This structure is used when the rotation track of the door is small and the size of the household bag cannot be guaranteed. When the door is opened, it is fixed by the buckle hardware. When the door is closed, it is untied by the buckle hardware to close the door one by one. Therefore, the opening and closing track of a door is small, so that the door can be opened and closed smoothly. Fire, smoke and heat insulation normally open fire doors and folding fire doors are new fire door hardware systems with smoke resistance, fire type certification and standard.