Abstract: An improved flexible-walled, bag-type container of the kind used for the storage of parenteral fluids such as saline solutions and blood, and for the administration of these fluids to patients under pressure. The container is characterized in one embodiment by relatively heavy gauge exterior walls formed of two bonded flexible sheets and an additional flexible interior wall of relatively light gauge. One peripheral portion of this additional wall member is bonded to an intermediate portion of one exterior wall and the remaining portions of the flexible wall member, that are co-extensive with the outer peripheral portions of the exterior walls, are bonded together. The container then has a first chamber for the liquid and a second chamber that can be expanded by means of an external pumping apparatus for forcing the liquid from the first chamber under pressure through a conduit.