An active bolster for an automotive vehicle includes a bladder that inflates an interior trim area of the vehicle to provide a cushion to an occupant during an impact. The bladder has a first wall and a second wall cooperatively defining an interior cavity. The bladder has a two stage vent for venting inflation gas supplied into the cavity during an impact event. The vent has a first aperture defining a first predetermined flow area when a pressure difference across the vent is substantially zero. A bendable member defines at least in part the first aperture. A weakened seam joins the bendable member to an adjacent feature of the bladder. When there is a predetermined pressure difference across the vent, the weakened seam is ruptured and the bendable member deflects to a second position defining a second flow area greater than the first flow area.
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