Abstract: An apparatus (10) for helping to protect an occupant of a vehicle includes an inflatable vehicle occupant protection device (14). An inflation fluid source (18) is actuatable to provide inflation fluid for inflating an inflatable volume (16) of the protection device (14). The apparatus (10) also includes a reaction plate (20) that includes at least one vent opening (40) and a retainer (60) that is connectable with the reaction plate (20). A vent part (80) has a first condition blocking inflation fluid flow through the at least one vent opening (40) and a second condition permitting inflation fluid flow through the at least one vent opening. The apparatus (10) further includes an actuator (120) for moving the vent part (80) from one of the first and second conditions to the other of the first and second conditions. The vent part (80) has a portion (104) that maintains the vent part in the other of the first and second conditions when moved to the other of the first and second conditions.