An apparatus (24) for inflating an inflatable vehicle occupant protection device (22) comprises a container (40) which defines a chamber (42) for material which effects inflation of the protection device. The container (40) includes an opening (60) of a flow area through which fluid flows to inflate the protection device (22). A rupturable closure (64) blocks fluid flow through the opening (60) in the container (40). A first actuatable initiator (164), upon actuation, effects the rupture of the closure (64). A member (120) is movable from a first position in which the flow of fluid through the opening (60) is unrestricted when the closure (64) is ruptured. The member (120) is movable to a second position in which fluid flow through the opening (60) is restricted by a portion of the member to reduce the flow area of the opening. A second actuatable initiator (162), upon actuation, moves the member (120) from the first position to the second position and effects the rupture of the closure (64).