This type of shutter is used to exclude any fires by closing the duct with a REI120 panel. In gravity and pneumatic version. The particular advantage of this type of damper lies in allowing the passage in the complete section of the pipe in which it is placed, since the closing diaphragm is in the open position, outside the section of the pipe. This important detail ensures that the diaphragm is always intact over time. The lower side can be opened to allow any materials that may be deposited during work to come out.